JP5619965B2 - Centrifuge - Google Patents

Description

  The present invention relates to a centrifuge for concentrating or dewatering sludge with a centrifuge.

In order to dispose of sludge generated when organic waste (raw solution) such as waste water and human waste is subjected to solid-liquid separation, biological treatment, physical treatment, etc., it is efficient for disposal and effective use. It is necessary to concentrate and dehydrate, and there is a need for a low water content in concentrated sludge and dehydrated sludge.
Therefore, in recent years, in the sludge treatment using a centrifugal separator, in order to improve the concentration performance and dewatering performance, a “two-component method” is performed in which two types of flocculants are added to the sludge for concentration and dewatering ( For example, see Patent Documents 1 and 2).

  In the “two-component method”, the flocculant used depends on the type of solid-liquid separator (centrifuge, belt press, screw press, etc.), but in the case of a centrifuge, usually (1) inorganic flocculant Using two solutions of polyferric sulfate solution and (2) amphoteric polymer flocculant solution as polymer flocculant. First, the inorganic flocculant solution (first liquid) is injected into the sludge, A molecular flocculant solution (second liquid) is injected.

  In the sludge dewatering process using a centrifuge, the "two-component method" reduces the water content of the dehydrated sludge and increases the clarification of the dehydrated separation solution compared to the "one-component method" using only the polymer flocculant ( Improvement of SS recovery rate) Furthermore, phosphorus (eutrophication substance) can be removed from the dehydrated separation liquid by using an inorganic flocculant in combination.

  In addition, the sludge dewatering treatment by the belt press machine is performed by first injecting the polymer flocculant solution (first liquid) into the sludge and then injecting the inorganic flocculant solution (second liquid). The method of use, the method of operation, and the flocculant are selected depending on the product.

JP-A-7-256300 (paragraph [0005]) JP-A-8-71600 (paragraph [0021] and FIG. 1)

In the sludge dewatering process by the conventional “two-component method” using a centrifugal separator, when two kinds of flocculant solutions are injected into the sludge in order to reduce the water content of the dewatered sludge, the following problems occur.
(1) The amount of chemicals used increases, leading to an increase in operating costs and complicated operation management.
(2) When a large amount of the inorganic flocculant solution is injected, the pH of the chemical sludge is greatly lowered, which may affect the concentration treatment and dehydration treatment, and may corrode the inside of the centrifuge.
(3) Therefore, if alkaline chemicals (caustic soda solution) or the like is injected into the chemical mixed sludge in order to neutralize the low pH chemical mixed sludge, the operation cost will be further increased, and the operation management will be further complicated.
(4) In addition, when a large amount of chemicals is injected into sludge, various chemical components may remain in concentrated sludge and dewatered sludge at high concentrations, which may hinder effective use (composting and fueling).

  Conversely, if the amount of the flocculant (inorganic or polymer) is suppressed so as not to increase the operating cost and complicated operation management, the water content of the separated material (for example, dehydrated sludge) cannot be reduced, making it difficult to handle. In addition, the volume of the separated material increases, which hinders subsequent disposal.

Therefore, there is a method of injecting the inorganic flocculant solution into the centrifuge (“in-machine injection method”) in order to achieve a stable low water content of the dewatered sludge without increasing the injection amount of the flocculant solution.
In this in-machine injection method, the polymer flocculant is injected into the sludge as the first liquid in the reverse order to the conventional “two-component method”, then supplied to the centrifuge, and solid-liquid separation (concentration) in the centrifuge. In the state where the dehydration has progressed to some extent, an inorganic flocculant is injected as the second liquid.

  However, in this in-machine injection method, compared to the conventional “two-component method” in which two types of flocculant, inorganic flocculant and polymer flocculant, are added to the sludge to produce a strong flocculant floc, the sludge has a higher level in the initial stage. Since only the molecular flocculant is added, it is difficult to produce strong flocs that are easy to separate into solid and liquid, and the solid-liquid separation performance at the initial stage of the centrifuge decreases, and sludge treatment is required to obtain the target moisture content. There was a problem that measures such as reducing the amount had to be taken.

  In addition, the water content of dewatered sludge can be reduced by the in-machine injection method, but the reaction time between the coagulated sludge (sludge into which the polymer coagulant is injected) and the inorganic coagulant component in the centrifuge is extremely large. Because it becomes shorter, it is difficult to clarify the separation liquid (improvement of SS recovery) and remove phosphorus from the separation liquid, and it affects the solid-liquid separation performance itself. There was a problem of stagnation.

  Furthermore, regarding the removal of phosphorus from the separation liquid, in the conventional “two-component method”, since the inorganic flocculant solution is injected into the sludge in advance, the phosphorus contained in the sludge is, for example, polyferric sulfate (inorganic flocculant). It reacts to become an insoluble phosphorus compound (iron phosphate: FePO4), which prevents phosphorus from transferring to the dehydrated (concentrated) separation liquid and returning to the wastewater treatment facility, but in the in-flight injection method, sludge and inorganic flocculant components The generation time of insoluble phosphorus compounds does not progress because the reaction time with the water becomes extremely short, and the dehydrated separation liquid containing phosphorus is returned to the wastewater treatment facility as return water, mixed into the treated water and drained, and discharged to the destination. In addition to promoting eutrophication, there was a challenge that could exceed the quality of discharged water.

  In addition, in order to solve the above-mentioned problems of solid-liquid separation performance and phosphorus removal in the in-machine injection method, it is conceivable to inject a large amount of inorganic flocculant into the sludge. The problem you have will occur.

  Normally, when the sludge is concentrated or dehydrated with a centrifuge, various flocculant solutions are injected into the sludge, but the inorganic flocculant solution is stopped and stopped (no flow, drying proceeds) If this happens, it will harden, which will hinder the injection and operation. In particular, when the inorganic flocculant solution is discharged from the pores, there is a problem that countermeasures against clogging must always be taken.

  In addition, the inorganic flocculant solution supply pipe also tends to solidify at the junction with other pipes, the curved (refractive) part, the inlet part, etc., and when the solid grows, it clogs and causes inorganic agglomeration. There was a problem that the supply of the inorganic flocculant solution as the agent solution was stopped, which hindered the concentration treatment and the dehydration treatment. In addition, when a large amount of the inorganic flocculant solution is injected into the sludge, not only the flocculant sludge supply pipe (sludge supply pipe) but also the sludge supply pipe outlet opening in the centrifuge and the inside of the centrifuge This problem also occurs at the sludge supply port provided in the sludge supply chamber, which interferes with the concentration and dehydration processes.

  Therefore, it is conceivable to install a cleaning facility in the supply pipe, etc. However, when pipe cleaning is performed together with centrifuge cleaning after the completion of concentration and dehydration, the cleaning water is usually supplied mainly to the sludge supply pipe. Therefore, the supply pipe for the inorganic flocculant solution and the sludge supply chamber in the centrifuge cannot be cleaned sufficiently, and installing multiple cleaning facilities to obtain a sufficient cleaning effect will not only increase the construction cost, However, there is a problem that operation management and maintenance inspection become complicated.

  In addition, balance adjustment is very important for a centrifuge that rotates at high speed, but if multiple cleaning facilities are installed in the centrifuge in a complicated manner, the balance adjustment becomes very difficult, and if the balance is lost due to a trivial matter, it will be serious. There was a problem that could cause a serious accident.

  When a cleaning facility is provided for removing and cleaning the lump of the inorganic flocculant and preventing clogging, tap water or groundwater is usually used, which causes an increase in operating costs such as water charges.

  The present invention has been made to solve the above-described problems, and solid-liquid separation is progressing during the transition to the separated discharge side of the pool formed between the outer trunk bowl and the inner trunk screw. Agglomerated sludge (separated sludge) and inorganic flocculant can be reacted efficiently and reliably, and the separated liquid can be further separated from the separated sludge, and the water content of the separated product (dehydrated sludge) can be reliably reduced. A centrifuge that can inject inorganic flocculant directly into the separated sludge, can be injected immediately without reducing the flocculation effect of the inorganic flocculant, and can stably maintain the high solid-liquid separation performance of the centrifuge. The purpose is to provide.

  A centrifugal separator according to the present invention supplies an inorganic flocculant and a polymer flocculant to sludge, and separates the sludge formed with flocks from a separated substance by a centrifuge provided with an outer trunk bowl and an inner trunk screw. An inorganic flocculant injection tube for injecting an inorganic flocculant into a sludge supply chamber disposed in the inner cylinder screw and provided with a sludge supply port and a flocculant outlet, in a centrifuge for solid-liquid separation into liquid And an inorganic flocculant discharge hole provided in the inorganic flocculant injection pipe and a water supply pipe connected to the inorganic flocculant injection pipe.

  The centrifugal separator according to the present invention is provided with a partition plate in the sludge supply chamber.

  The centrifugal separator according to the present invention includes a phosphorus concentration measuring device that measures the phosphorus concentration of the separation liquid.

  The centrifugal separator according to the present invention includes a separation liquid circulation pipe for supplying the separation liquid to the water supply pipe.

According to the centrifugal separator of the present invention, the inorganic flocculant is injected into the inside of the sludge supply chamber provided in the inner cylinder screw of the centrifuge and provided with the sludge supply port and the flocculant outlet. By providing the inorganic flocculant injection pipe, the inorganic flocculant is directly injected into the sludge supply chamber using the inorganic flocculant injection pipe, and between the outer trunk bowl and the inner trunk screw via the flocculant outlet. Can be supplied to the separated discharge side of the pool formed. As a result, the inorganic flocculant can be directly injected again into the agglomerated separated matter (separated sludge) that has moved to the separated product discharge side and solid-liquid separation is progressing, and thus has many excellent effects as follows.
(1) The separated sludge and the inorganic flocculant can be reacted efficiently and reliably, and the separated liquid can be further separated from the separated sludge, and the water content of the separated product (dehydrated sludge) can be reliably reduced.
(2) Since the inorganic flocculant can be directly injected again into the separated sludge, it can be injected immediately without reducing the flocculation effect of the inorganic flocculant, and the high solid-liquid separation performance of the centrifuge can be stably maintained. .
(3) Since the inorganic flocculant is directly injected, waste is eliminated and the amount of injection can be easily adjusted, so that the amount of inorganic flocculant used can be reduced. As a result, an increase in operating cost can be suppressed, and complicated operation management can be avoided.
(4) Before the inorganic flocculant is directly injected into the separated sludge, the inorganic flocculant is injected into the sludge in advance, so that the phosphorus contained in the sludge surely reacts with the inorganic flocculant to form an insoluble salt. Transition to the separation liquid can be suppressed, and the clarity of the separation liquid (high SS recovery rate) can be obtained. Thereby, deterioration of the water quality (phosphorus, SS, organic matter) of the return water to the wastewater treatment facility can be prevented, and appropriate discharged water quality can be maintained.
(5) Proper injection of the inorganic flocculant can prevent the sludge from lowering the pH of the sludge, so that the centrifuge can be prevented from corroding and degrading, and there is no need to install a neutralization facility. Management and repair costs can be reduced. Furthermore, since chemicals are not injected excessively, dewatered sludge can be effectively used (composted or fueled).
(6) By directly injecting the inorganic flocculant into the separated sludge, the dehydrated sludge can be reduced in water content and the volume is reduced, so that it is easy to handle and reduces the work and cost required for disposal. be able to.
(7) Since the inorganic flocculant is injected into the sludge in advance, it is possible to generate strong flocculent flocs (aggregated sludge) that are easy to separate into solid and liquid, ensuring the solid-liquid separation performance in the initial stage of the centrifuge, and the throughput Can maintain fitness.

In the present invention, the following operation and effect can be obtained by connecting a water supply pipe to the inorganic flocculant injection pipe so that water can be supplied to the inorganic flocculant injection pipe.
(1) By supplying water to the inorganic flocculant injection tube during operation of the centrifuge, the inorganic flocculant solution that is highly concentrated and easily solidified can be instantly diluted, so that the inorganic flocculant solution can be quickly and stably stabilized. It can be discharged from the inorganic flocculant discharge hole of the injection pipe to the sludge supply chamber and supplied from the flocculant outlet to the separated discharge side of the outer shell bowl.
(2) Since the inorganic flocculant solution is diluted and increased as described above, the inorganic flocculant solution can be directly and universally supplied to the separated product moving to the separated product discharge side. The inorganic flocculant can be reacted, and the water content of the separated product can be reduced more efficiently and reliably.
(3) Since the inorganic flocculant solution can be diluted quickly, a high concentration inorganic flocculant solution can be used, which enables downsizing of the solution storage (dissolution) tank and injection pump. It is effective in reducing cost and installation area.

Furthermore, by supplying water to the inorganic flocculant injection tube during the operation stop process of the centrifuge, the following effects can be obtained.
(1) Inorganic coagulant supply pipes, inorganic coagulant injection pipes, inorganic coagulant discharge holes, sludge supply chambers, coagulant outlets, and other parts where inorganic coagulants that tend to adhere and solidify can be reliably washed, and inorganic coagulation It is possible to prevent clogging and blockage by the agent.
(2) The inorganic flocculant discharge hole and the flocculant outlet, which have a particularly small diameter, are likely to be clogged. Once clogged, large maintenance work is required. ), The adhesion-solidification-growth of the flocculant can be reliably prevented, and the centrifuge can be operated stably.
(3) There is no need to install multiple complicated cleaning facilities, and the water supply to the inorganic flocculant injection tube can reliably clean the inorganic flocculant system that is likely to clog or clog the centrifuge, resulting in equipment costs. Can be prevented, and maintenance work can be prevented from increasing, which is also beneficial for proper maintenance of the centrifuge.

Furthermore, in the present invention, a partition plate is provided between the sludge supply port in the sludge supply chamber and the flocculant outlet, and an inorganic flocculant discharge hole of the inorganic flocculant injection pipe is opened on the side of the flocculant outlet of the partition plate. As a result, the following effects can be obtained.
(1) The inorganic flocculant solution supplied from the inorganic flocculant discharge hole of the inorganic flocculant injection pipe into the sludge supply chamber can be reliably guided to the flocculant outlet without being diffused in the sludge supply chamber.
(2) The inorganic flocculant solution smoothly guided to the flocculant outlet by the partition plate and allowed to react with the separated sludge moving to the separated discharge side evenly and quickly.
(3) When a flocculant outlet is provided near the two-stage taper of the outer shell bowl, the inorganic flocculant solution can be reinjected directly and quickly into the separated sludge from which the separated liquid has been separated by solid-liquid separation. Further, the separated liquid can be further separated from the separated sludge, and the water content of the separated product (dehydrated sludge) can be reliably reduced.
(4) Further, when the inorganic flocculant discharge hole of the inorganic flocculant injection pipe is opened near the flocculant outlet, the washing water is discharged from the inorganic flocculant discharge hole toward the flocculant outlet, The flocculant outlet through which the inorganic flocculant that easily adheres and solidifies passes can be reliably and efficiently washed.

Further, by providing an inorganic flocculant injection pump for supplying the inorganic flocculant to the sludge together with the inorganic flocculant injection pump for supplying the inorganic flocculant to the inorganic flocculant injection pipe, the following effects can be obtained.
(1) By supplying an inorganic flocculant solution to the sludge in advance separately from the inorganic flocculant, the phosphorus component contained in the sludge can react with the inorganic flocculant to be converted into an insoluble salt and removed together with the separated substance. Therefore, the transfer of the phosphorus component to the separation liquid and the reflux to the wastewater treatment facility can be reliably prevented. In addition, by supplying the inorganic flocculant solution to the sludge in advance, it is possible to generate strong flocculated flocs (aggregated sludge) that are easy to separate into solid and liquid, and the SS recovery rate is improved, so that the SS of the separated liquid can also be reduced, and The inflow load to the processing equipment can be reduced.
(2) In re-injection of the inorganic flocculant by the inorganic flocculant injection pipe, the inorganic flocculant is mainly supplied to the separated sludge that has been transferred to the separated product discharge side, and the separation that has been transferred to the sludge and separation liquid discharge side. It is difficult to come into contact with the liquid, so the phosphorus component contained in the separation liquid (which is a eutrophication substance and is not easy to remove by wastewater treatment) is discharged with the separation liquid and returned to the wastewater treatment facility, etc. This can be prevented by supplying the inorganic flocculant to the sludge in advance.
(3) Regarding the injection of the inorganic flocculant, it is preferable to separately provide an inorganic flocculant injection pump and an inorganic flocculant supply pump depending on the operating conditions and processing conditions, and operate both pumps separately. May be used in both applications. As a result, the equipment cost and running cost can be reduced, and the space can be saved.

Furthermore, in the present invention, when an inorganic flocculant solution is supplied to sludge in advance to remove phosphorus from the separation liquid, a phosphorus concentration measuring device that measures the phosphorus concentration of the separation liquid in order to grasp the state of phosphorus removal. By providing, the following effects can be obtained.
(1) When the phosphorus concentration of the separation liquid is high, adjust the inorganic flocculant supply amount by the inorganic flocculant supply pump to increase, and conversely, decrease the inorganic flocculant supply amount when the phosphorus concentration is low. It can be adjusted, and phosphorus removal from the separation liquid can be performed stably.
(2) Supplying an inorganic flocculant to sludge unnecessarily to remove phosphorus from the separation liquid will lead to an increase in operating costs such as chemical costs, but depending on the phosphorus concentration of the separation liquid, an appropriate inorganic flocculant supply pump Therefore, it is possible not only to reliably remove phosphorus but also to suppress an increase in operating cost.
(3) Furthermore, by providing a controller that controls the operation of the inorganic flocculant supply pump based on the measurement value of the phosphorus concentration measuring device, the amount of inorganic flocculant supplied to the sludge can be quickly and reliably adjusted according to the situation. It can be controlled, can perform stable processing, and is effective in reducing operating costs, saving labor, and reducing work.

The following effects can be obtained by providing a separation liquid circulation pipe for supplying a separation liquid to the water supply pipe and circulating the separation liquid through the water supply pipe.
(1) Separation liquid can be used effectively, which can reduce operation costs such as water usage fees and is effective for resource saving.
(2) Since the separation liquid that circulates originally constitutes sludge (= similar properties), by supplying the separation liquid to the centrifuge, foreign liquids (tap water and groundwater) are supplied. Compared with the case where it does, the influence on a centrifugation process (solid-liquid separation performance) can be excluded, and the stable efficient operation can be performed.
(3) Although the phosphorus component remains in the separation liquid, since the separation liquid is recycled, it reacts again with the inorganic flocculant in the inorganic flocculant injection tube to form an insoluble salt. Can be removed. Further, when the flocculant component remains in the separated liquid, the remaining flocculant can be reused by circulating the separated liquid, and a saving in the amount of flocculant used can be expected.
(4) When supplying water to the centrifuge and washing (stopping operation), circulating the separation liquid increases the amount of water supplied to the centrifuge (= wash water), and the water pressure and flow rate in the centrifuge As a result, the cleaning effect can be enhanced. If all of the cleaning water is covered with tap water, it is necessary to increase the operating cost and increase the size of the cleaning equipment. The cleaning effect can be increased without increasing the size of the equipment.

  In the present invention, by using an inorganic flocculant (such as polyferric sulfate, ferric chloride, polyaluminum chloride, etc.) as the flocculant, solid components of the sludge are reliably agglomerated to produce highly separable sludge flocs. In addition to being able to react with the phosphorus component contained in the sludge, it can be removed as an insoluble salt.

In the present invention, amphoteric polymer flocculants, cationic polymer flocculants, anionic polymer flocculants, and nonionic polymer flocculants are used as the polymer flocculants.
In this case, after adding an inorganic flocculant, such as polyiron, to the sludge to produce fine flocculent flocs, the amphoteric polymer flocculant is supplied to further agglomerate to produce strong sludge flocs. it can.

  In addition, cationic polymer flocculants, anionic flocculants, and nonionic polymer flocculants that can generate relatively strong sludge flocs alone may be used. For example, when a small amount of inorganic flocculant is injected into sludge in advance. Can produce a strong sludge floc by using an anionic polymer flocculant when a large amount of the cationic polymer flocculant is injected. The nonionic polymer flocculant is effective when dewatering the water sludge and the like.

Embodiment 1 FIG.
1A is a cross-sectional view showing a centrifugal separator according to Embodiment 1 of the present invention, and FIG. 1B is an enlarged cross-sectional view of the main part of FIG.
The centrifugal separator according to the present invention supplies an inorganic flocculant and a polymer flocculant to sludge, and the flocs formed sludge is solidified by a centrifuge 1 having an outer trunk bowl 3 and an inner trunk screw 4. Sludge which is liquid-separated and is provided with an inorganic flocculant injection pipe 23 having an inorganic flocculant discharge hole 23a, which is disposed in the inner cylinder screw of the centrifuge, and which is provided with a sludge supply port 7a and a flocculant outlet 7b. The basic structure is such that the inorganic flocculant is reinjected into the supply chamber 7.
The centrifuge according to the first embodiment includes a centrifuge 1 that solid-liquid separates sludge supplied with an inorganic flocculant and a polymer flocculant into a separated product and a separated liquid, and a sludge storage tank 11 that stores sludge. The polymer flocculant storage tank 12 for storing the polymer flocculant solution and the inorganic flocculant storage tank 13 for storing the inorganic flocculant solution are provided. The detailed structure will be described below. .

  First, the centrifuge 1 includes a casing 2 having a separation liquid discharge port 2a on one end side and a separated product discharge port 2b on the other end side, and an outer body bowl rotatably disposed in the casing 2 3, an inner body screw 4 rotatably disposed in the outer body bowl 3, a rotational drive unit 5 that rotationally drives the outer body bowl 3, and a rotational drive unit that rotationally drives the inner body screw 4 6 and a differential speed adjuster (not shown) for providing a rotational difference between the outer body bowl 3 and the inner body screw 4, and a concentration / dehydration zone between the outer body bowl 3 and the inner body screw 4. As a result, a pool 10 is formed.

  The outer body bowl 3 has a cylindrical body 3a having a cylindrical shape on the separation liquid discharge side from an intermediate portion thereof, and tapered portions (narrow diameter portions) formed on the separation material discharge side are defined as two-stage tapers 3b and 3c. Forming. The two-step taper 3b, 3c is manufactured such that the two-step taper 3b below the water surface WL has a steep inclination and the two-step taper 3c on the water surface WL has a gentle inclination. Such a two-stage taper 3b, 3c enables the squeezing effect to the coagulated sludge by the screw blade 4c under the water surface and the extension of the residence time in the pool 10, and in particular, the two-stage taper 3b that strongly receives the centrifugal effect. The residence time can be increased. Even if the tapered portion formed on the separated material discharge side of the outer shell bowl 3 is a one-step taper 3d, high centrifugal separation (dehydration) performance can be obtained.

  The inner cylinder screw 4 includes a cylindrical straight body part 4a formed on the separation liquid discharge side from an intermediate part thereof, an inner cylinder taper 4b formed on the separated product discharge side, and the straight body part 4a and the inner cylinder screw 4a. The screw blade 4c is integrally formed on the outer periphery of the body taper 4b.

  Inside the inner cylinder screw 4 is formed a sludge supply chamber 7 extending over the straight body portion 4a and the inner cylinder taper 4b. The sludge supply chamber 7 includes a sludge supply port 7a, a flocculant outlet 7b, A partition plate 8 is provided. More specifically, the sludge supply chamber 7 communicates with the outer body bowl 3 through a sludge supply port 7a provided in the straight body portion 4a of the inner body screw 4, and the flocculant outlet 7b is provided on the inner cylinder taper 4b, and on the inner peripheral surface of the inner cylinder taper 4b, the coagulant outlet 7b and the sludge supply port 7a on the straight body 4a side are provided in the vicinity of the coagulant outlet 7b. A partition plate 8 for partitioning is provided.

  The partition plate 8 is usually installed in a donut shape inside the sludge supply chamber 7, and a clearance (interval) with a sludge supply pipe 14 to be described later is normally set to 10 mm or less. By installing such a partition plate 8, the inorganic flocculant supplied into the sludge supply chamber 7 from the inorganic flocculant discharge hole 23a described later is suppressed / prevented from diffusing in the sludge supply chamber 7. Can do.

  In the centrifuge 1 configured as described above, the sludge supply chamber 7 of the inner cylinder screw 4 is connected to a sludge supply pipe 14 that supplies the sludge of the sludge storage tank 11, and the sludge supply pipe 14 is connected to the sludge supply pipe 14. A sludge supply pump 15 is provided. The sludge supply pipe 14 is supplied with the polymer flocculant solution supplied from the polymer flocculant reservoir 12 to the sludge flowing through the sludge supply pipe 14 (sludge being supplied to the sludge supply chamber 7). An inorganic flocculant supply pipe 20 that supplies the inorganic flocculant solution in the agent supply pipe 16 and the inorganic flocculant storage tank 13 is connected.

  The polymer flocculant supply pipe 16 is provided with a polymer flocculant supply pump 17, a flow meter 18, and an open / close valve 19 from the polymer flocculant reservoir 12 side. Are each provided with an inorganic flocculant supply pump 21 and a flow meter 22 from the inorganic flocculant reservoir 13 side. An electric valve is used as the normal on-off valve.

  The inorganic flocculant is again injected into the pool 10 from the inorganic flocculant reservoir 13 through the inorganic flocculant injection pipe 23 and the flocculant outlet 7b. The inorganic flocculant injection pipe 23 is generally in the shape of a pipe and extends inside the sludge supply pipe 14 together with the sludge supply pipe 14 and is provided with an inorganic flocculant discharge hole 23 a that opens in the sludge supply chamber 7. The inorganic flocculant discharged from the flocculant discharge hole 23a into the sludge supply chamber 7 passes through the flocculant outlet 7b and flows out into the pool 10.

Next, the operation will be described.
Sludge is supplied from the sludge storage tank 11 to the centrifuge 1 by the sludge supply pump 15. In the supply process, the sludge is supplied from the inorganic flocculant storage tank 13 to the inorganic flocculant supply tank 13. At 21, the inorganic flocculant is supplied (previous stage supply) and mixed, and then the polymer flocculant is supplied (line supply) from the polymer flocculant storage tank 12 by the polymer flocculant supply pump 17, mixed, and centrifuged. It is sent to the sludge supply chamber 7 of the separator 1.

  The agglomerated sludge produced by mixing the sludge and the both aggregating agents is put into a sludge supply chamber 7 provided in the inner cylinder screw 4, and sequentially between the inner cylinder screw 4 and the outer cylinder bowl 3 through the sludge supply port 7 a. Supplied to the pool 10 to be formed. The agglomerated sludge undergoes solid-liquid separation while receiving a strong centrifugal force in the pool 10, and the dewatered sludge that is a separated product is produced by the screw blades 4 c that rotate at the rotational difference (different speed) between the outer body bowl 3 and the inner body screw 4. Is transferred to the separation discharge side and discharged from the separation discharge port 2b. The separated liquid (dehydrated separated liquid) separated from the coagulated sludge is discharged from the separated liquid discharge port 2a on the separated liquid discharge side due to the difference in water level from the separated discharge side.

The agglomerated sludge supplied to the pool 10 is solid-liquid separated while moving to the separated product discharge side by the screw blade 4c, and is scraped up on the water surface WL as a separated sludge. The inorganic flocculant solution is re-injected through the inorganic flocculant discharge hole 23a of the inorganic flocculant injection pipe 23 (the latter-stage injection), and solid-liquid separation further proceeds, and is discharged from the separated product outlet 2b as dehydrated sludge.
The reinjected inorganic flocculant flows out to the pool 10 from the flocculant outlet 7b provided in the inner cylinder screw 4, and is scraped up on the water surface WL while moving to the separated material discharge side by the screw blade 4c. Mix with separated sludge.

  The injection position of the inorganic flocculant solution in the pool 10 is preferably in the vicinity of the two-stage taper 3b, 3c. As described above, the inorganic flocculant solution is re-injected when the separated sludge is lifted onto the water surface WL (post-injection). By adopting such a structure, water (separated liquid) can be efficiently and reliably removed from the separated sludge into which the inorganic flocculant has been reinjected.

  FIG. 1B shows the reinjection of the inorganic flocculant and the dewatered state of the separated sludge by the inorganic flocculant injection pipe 23 in the centrifuge 1, and the reinjection location of the inorganic flocculant is the pool. 10 is preferable on the water surface WL, and the concentration and dehydration have progressed to some extent, and by reinjecting the inorganic flocculant into the separated sludge that has been scraped up on the water surface WL while moving to the separated product discharge side, it is efficient and reliable. In addition, sludge concentration and sludge dewatering are performed.

  The centrifugal separator according to the first embodiment described above is configured as described above, thereby dramatically improving the moisture content (concentration rate) that is important in centrifugal separation processing (centrifugal dehydration processing and centrifugal concentration processing) ( The dehydration performance can be improved), the phosphorus concentration of the separation liquid can be reduced, and the SS recovery rate can be maintained at a high level.

Example 1.
An example of operation of the centrifugal separator according to the first embodiment will be described below. The implementation conditions are high-efficiency centrifugal dehydrator for sewage digested sludge, machine operating conditions are processing volume 1.5m ³ / h, centrifugal effect 2500G, amphoteric polymer flocculant injection (supply) rate 1.2%, A comparison was made between the conventional apparatus and the centrifugal separator according to the present invention under substantially the same conditions of a differential speed of 1.3 to 1.5 revolutions. The digested sludge concentration is 1.5%, the phosphorus concentration is about 600 mg / L, and the pH is 7.4. Examples are shown in Table 1.

  In the centrifugal separator (conventional (1)) employing the usual two-liquid method, polyiron is supplied to the sludge supply pipe (line supply) as an inorganic flocculant, and then the amphoteric polymer flocculant is also injected into the line for centrifugal dehydration. As a result, the moisture content of the dewatered sludge was 78.5%, the phosphorus concentration of the separated liquid was 10 mg / L, and the SS recovery rate was 98%. With this device, good results were obtained in both the phosphorus concentration of the separation liquid and the SS recovery rate, but the water content of the dewatered sludge, which is important in centrifugal dewatering, is only 78.5%, and further reduction of the water content is required.

  In addition, in the centrifugal separator (conventional (2)) adopting the in-machine injection method, the amphoteric polymer flocculant is line-injected into the sludge supply pipe, and then polyiron is injected into the centrifugal dehydrator as an inorganic flocculant and then centrifuged. When dehydrated, the water content of the dewatered sludge was 74.0%, the phosphorus concentration of the separated liquid was 250 mg / L, and the SS recovery rate was 96%. In this device, the moisture content of the dewatered sludge was reduced, but the SS recovery rate was not good, and the phosphorus concentration of the separation liquid was very high. This is because the contact (reaction) between the sludge and the inorganic flocculant was insufficient, and the generation of insoluble salts of phosphorus did not proceed. To prevent reflux of the separated liquid with high phosphorus and SS concentrations to the wastewater treatment facility, Separate measures must be taken.

  On the other hand, in the centrifugal separator according to the present invention (the present invention (1) and the present invention (2)), polyiron is supplied to the sludge supply pipe 14 as the inorganic flocculant (pre-stage supply), and then the amphoteric polymer. The flocculant is supplied in line, and polyiron is directly injected into the sludge supply chamber 7 using the inorganic flocculant injection pipe 23, and reinjected into the separated product discharge side of the pool 10 through the flocculant outlet 7b ( As a result, the water content of the dewatered sludge was 75.0%, and the phosphorus concentration of the separated liquid was 10 to 90 mg / L. In the centrifugal separator according to the present invention, the water content of the dewatered sludge is sufficiently reduced, the SS recovery rate is good, and the phosphorus concentration of the separation liquid is also reduced. In particular, the present invention (2) shows that the phosphorus concentration of the separation liquid is greatly reduced to 10 mg / L, and it has been proved that it is very effective as a sludge dewatering treatment.

  As described above, the centrifugal separator according to the present invention has not only good separation liquid properties (phosphorus concentration and SS recovery rate) even under the same operating conditions and chemical injection rate as in the prior art, but also greatly increases the water content of dehydrated sludge. Can be reduced. In addition, what is necessary is just to reduce the quantity of the inorganic flocculant supplied in the front | former stage, when the phosphorus (phosphorus concentration) contained in sludge falls. Also, if you want to change the operation method due to changes in sludge properties or increase / decrease in the processing volume, the conventional (1) method (two-liquid method) or conventional (2) (in-machine injection) can be performed by operating the valve or supplying pump. ) Is a versatile centrifuge that can be easily changed in operation.

Embodiment 2. FIG.
2A is a cross-sectional view showing a centrifugal separator according to Embodiment 2 of the present invention, FIG. 2B is an enlarged cross-sectional view of the main part of FIG. 2A, and the same components as those in FIG. A reference numeral is attached and a duplicate description is omitted.
In the centrifugal separator according to the second embodiment, a water supply pipe 26 is connected to an inorganic flocculant injection pipe 23 for an inorganic flocculant, and inorganic flocculant discharge holes 23a and 23b are provided at two locations of the inorganic flocculant injection pipe 23. The point that the two partition plates 8a and 8b are provided inside the centrifuge 1 and the point that the taper portion of the outer shell bowl 3 is formed as a one-stage taper 3d as the main body of the centrifuge 1 are described above. It is very different from 1. The purpose of supplying water to the inorganic flocculant injection pipe 23 by the water supply pipe 26 is mainly for washing when the centrifuge 1 is stopped and diluting the inorganic flocculant when the centrifuge 1 is operating.

  First, when cleaning the centrifuge, mainly when the centrifuge stops operating (processing), the cleaning water is supplied to the sludge supply pipe, and the sludge supply chamber and pool in the centrifuge are cleaned together with the sludge supply pipe. To do. However, the main purpose of such cleaning is to remove sludge remaining in the apparatus (sludge cleaning), and it is difficult to clean the flocculant injection system (especially washing away the inorganic flocculant that tends to adhere and solidify). In the case of the centrifugal separator according to the present invention, the coagulant outlets 7 b and 7 c provided in the inorganic coagulant discharge holes 23 a and 23 b of the inorganic coagulant injection pipe 23 and the inner cylinder screw 4 are provided in the sludge supply chamber 7. May be partitioned by partition plates 8a and 8b provided on the surface, and normal cleaning cannot sufficiently clean sludge and wash away the inorganic flocculant. Therefore, for stable centrifugal separation processing and equipment maintenance management, a water supply pipe 26 is connected to the inorganic flocculant injection pipe 23 to supply water, and a flocculant injection system (mainly inorganic flocculant injection pipe, inorganic flocculant discharge) The pores, the flocculant outlet) and the like can be reliably and sufficiently washed.

Next, in the injection of the inorganic flocculant into the centrifugal separator 1, for example, in the sludge dewatering process in the centrifugal dehydrator, the inorganic flocculant is reinjected into the separated product discharge side of the pool 10 using the inorganic flocculant injection pipe 23 ( In the case of subsequent injection), if the inorganic flocculant injection rate of the inorganic flocculant injection pipe 23 is 500 ppm, only a very small amount of 500 mL is injected with respect to 1 m ^{3 of} the supplied sludge. When the inorganic flocculant is directly injected as a stock solution, the solution concentration is very high and the injection amount becomes small. In such a case, it is difficult for the reinjected inorganic flocculant solution to quickly reach the separated sludge and to be mixed efficiently. That is, it becomes a local reinjection of the inorganic flocculant, so that the separated sludge cannot be sufficiently solid-liquid separated, which may hinder the sludge dewatering treatment (sufficiently low water content of the dewatered sludge).

  Therefore, the water supply pipe 26 is connected to the inorganic flocculant injection pipe 23 to supply water, and the inorganic flocculant solution to be injected later is diluted (usually diluted 2 to 10 times) to increase the amount of screw blades in the pool 10. The inorganic flocculant is quickly and evenly mixed with the separated sludge that has been scraped up on the water surface WL while moving to the separated product discharge side by 4c, and good dewatering performance is obtained, and the separated sludge is dehydrated sufficiently efficiently. can do.

  In the second embodiment, inorganic flocculant discharge holes 23a and 23b are provided at two locations on the inorganic flocculant injection pipe 23 in order to adjust the reinjection position of the inorganic flocculant in the pool 10 and to perform wide reinjection. However, it is preferable that the inorganic flocculant discharge holes 23a and 23b have a structure that can be closed from the outside by bolts (not shown).

  Since the dewatering performance varies depending on the re-injection position of the inorganic flocculant, the re-injection position of the inorganic flocculant is adjusted (changed) in consideration of the operating conditions and sludge properties. Normally, the moisture content of dewatered sludge decreases as the dewatering time (sludge retention time) after re-injection of the inorganic flocculant decreases, but if the inorganic flocculant remains on the separation liquid side and enters the separation liquid and flows out, Not only is the re-injection of the inorganic flocculant into the separated sludge above, the water content of the dewatered sludge is deteriorated, but the water quality of the separated liquid is also deteriorated.

  Therefore, for example, when polyiron is used as the inorganic flocculant, the pH of the polyiron solution is low, so when the pH of the separation liquid decreases, the injection position is changed to the separation discharge side (separation liquid discharge). The side inorganic flocculant discharge holes 23a are closed with bolts). If it is effective to re-inject the inorganic flocculant over a wide range depending on the operating conditions, sludge properties, etc., the centrifugal dehydrator 1 is fully opened without blocking the inorganic flocculant discharge holes 23a and 23b. You may drive.

  In the second embodiment, two partition plates 8a and 8b are provided, and the number, position, and shape of the partition plates 8a and 8b are the number and position of the inorganic flocculant discharge holes 23a and 23b, and the flocculant. Although it adjusts with the number and position of the outflow ports 7b and 7c, if the inorganic flocculant supplied from the inorganic flocculent discharge holes 23a and 23b can suppress and prevent in the sludge supply chamber 7, it will be especially limited. It is not a thing.

  Further, in the second embodiment, the taper portion of the outer shell bowl 3 of the centrifuge 1 is formed into a one-stage taper 3d. This is because the dewatered sludge scraping portion has a fixed angle structure, and the sludge to be treated Depending on the angle, use it properly. For example, it is preferable that the sludge with a large amount of inorganic components is difficult to scrape the agglomerated sludge with the screw blades 4c, so that the angle is gently inclined.

  In addition, in centrifugal dewatering of sludge containing a large amount of inorganic components, if the angle of the first stage taper 3d of the centrifugal separator 1 is steeply inclined, it is difficult to scrape the coagulated sludge, and from the surface of the pool 10 to the dewatered sludge discharge section. Since the distance and the residence time become shorter and the solid-liquid separation due to the centrifugal effect of the separated sludge on the water surface of the pool 10 does not sufficiently act and the dewatering performance is lowered, the slope is usually made gentle.

Embodiment 3 FIG.
FIG. 3 is a cross-sectional view showing a centrifugal separator according to Embodiment 3 of the present invention. The same components as those in FIGS.
In the third embodiment, the inorganic flocculant discharge holes 23a, 23b, 23c and the three partition plates 8a, 8b, 8c corresponding to the inorganic flocculant discharge holes 23a, 23b, 23c are disposed at three locations of the inorganic flocculant injection pipe 23, and the water supply pipe 26 differs from the first embodiment in that a water supply pump 28 is disposed downstream of the automatic opening / closing valve 27 in FIG.
The use and effect are the same as those of the first embodiment, adjustment of the reinjection position of the inorganic flocculant in the pool 10, wide reinjection of the inorganic flocculant into the separated sludge on the water surface, and the like. Is possible. Further, by providing a water supply pump 28 and a flow meter 29 for metered water supply in the water supply pipe 26, the inorganic flocculant can be surely diluted to an appropriate concentration while the centrifuge 1 is in operation. When the operation of the centrifuge 1 is stopped, the inside of the centrifuge 1 can be reliably washed with an appropriate amount of water, particularly the inorganic flocculant injection system.

  Normally, as shown in FIG. 2 (A), the inorganic flocculant solution is injected into the separated sludge (flocculated sludge whose solid-liquid separation has advanced by the centrifugal effect) that has been scraped up on the water surface WL of the pool 10, but the sludge Depending on the properties and processing conditions, as shown in FIG. 3, the inorganic flocculant solution may be injected later from the flocculant outlet 7b into the water surface WL near the separation liquid discharge port 2a. And the water quality of the separated liquid can be improved.

Embodiment 4 FIG.
FIG. 4 is a cross-sectional view showing a centrifugal separator according to Embodiment 4 of the present invention. The same components as those in FIGS.
In the fourth embodiment, in the pre-stage supply of the inorganic flocculant, the injection position is performed in front of the sludge sludge supply pump 15 (sludge suction side). That is, the fourth embodiment is greatly different from the first to third embodiments in that the inorganic flocculant supply pipe 20 is connected to the sludge supply pipe 14 on the suction side of the sludge supply pump 15. By setting it as such a structure, mixing of sludge and an inorganic flocculant is accelerated | stimulated by the sludge supply pump 15, and favorable and efficient dehydration performance can be obtained.

Embodiment 5. FIG.
FIG. 5 is a cross-sectional view showing a centrifugal separator according to Embodiment 5 of the present invention. The same components as those in FIGS.
In the fifth embodiment, a centrifugal separator using two types of inorganic flocculants is used. Therefore, a pre-stage inorganic flocculant storage tank 13A for storing an inorganic flocculant solution different from the inorganic flocculant storage tank 13 is newly added.

  Inorganic flocculants have different characteristics depending on their types. For example, ferric sulfate (polyiron) has a large specific gravity and is very effective for sludge dewatering treatment. However, since the pH is low and the buffering capacity is large, it is easy to lower the pH of the coagulated sludge. Polyaluminum chloride (PAC) is lighter in specific gravity than polyiron and inferior in dehydration performance (lower water content) to polyiron, but has a low pH buffering capacity and is difficult to lower the pH of the coagulated sludge. The action of removing phosphorus (insoluble chloride of phosphorus contained in the sludge) is the same for both polyiron and PAC. In other words, as an influence on the dehydration of the inorganic flocculant, for example, when polyiron having a low pH is used, it is effective to lower the moisture content of the dehydrated sludge. It is necessary to suppress the supply / injection amount (rate). On the other hand, when PAC is used, the pH of the coagulated sludge does not decrease so much and can be sufficiently supplied and injected, but the moisture content of the dewatered sludge does not decrease as compared with the case where polyiron is used. In consideration of such a situation, in the combined use of two types of inorganic flocculants, for example, when the sludge has a low pH, the flocculation effect or Ensures treatment performance such as phosphorus removal, and uses polyiron as an inorganic flocculant to be injected later, further reducing the moisture content of dewatered sludge, enabling stable and efficient dewatering of sludge To do.

  In such a centrifugal separator according to Embodiment 4, by utilizing the respective characteristics of the inorganic flocculant, excellent dewatering performance is achieved by using two kinds of inorganic flocculants in accordance with the sludge properties and operation treatment conditions. In addition, a dehydrated sludge having a low water content and a separation liquid having a good water quality can be obtained. Moreover, considering the centrifugal separation technology (apparatus surface, cohesiveness, etc.), the pH of each of the main body of the centrifugal separator 1, the coagulated sludge, the dewatered sludge, and the separation liquid is preferably near neutral. The combination of these two is effective.

Embodiment 6 FIG.
6 is a cross-sectional view showing a centrifugal separator according to Embodiment 6 of the present invention, FIG. 7 is an enlarged cross-sectional view showing the main part of FIG. 6, and the same components as those in FIGS. The duplicate explanation is omitted.
In the sixth embodiment, the inorganic flocculant is pre-supplied in the sludge supply chamber 7 of the centrifuge 1 (inorganic inorganic pre-stage supply), and the polymer flocculant is similarly supplied in the sludge supply chamber 7. (Polymer middle stage supply). Further, one kind of inorganic flocculant is used, and the water supply pipe 26 is branched into branch pipes 26a and 26b so that water can be supplied (washed and diluted) to the inorganic flocculant supply pipe 20 and the inorganic flocculant injection pipe 23. is there.

  More specifically, in the sixth embodiment, an inorganic flocculant supply pipe 20 for supplying an inorganic flocculant upstream and an inorganic flocculant injection pipe 23 for subsequent injection are connected to one inorganic flocculant reservoir 13. In addition, each of the inorganic flocculant supply pipe 20, the inorganic flocculant injection pipe 23, and the polymer flocculant supply pipe 16 extends in the sludge supply pipe 14. Further, the water supply pipe 26 is branched into the branch pipes 26a and 26b on the downstream side of the automatic opening / closing valve 27, and one branch pipe 26a is connected to the downstream side of the flow meter 25 of the inorganic flocculant injection pipe 23 and the other The branch pipe 26 b is connected between the inorganic flocculant storage tank 13 of the inorganic flocculant supply pipe 20 and the inorganic flocculant supply pump 21. The branch pipe 26a of the water supply pipe 26 is provided with an open / close valve 37, and the branch pipe 26b is provided with an open / close valve 38. The inorganic flocculant supply pipe 20 is provided with an inorganic flocculant supply pump 21 and a flow meter 22, and the inorganic flocculant injection pipe 23 is provided with an inorganic flocculant injection pump 24 and a flow meter 25.

  In the inorganic flocculant supply pipe 20, the inorganic flocculant injection pipe 23, and the polymer flocculant supply pipe 16 that are extended and disposed in the sludge supply pipe 14, the inorganic flocculant supply pipe 20 opens at the tip of the sludge supply chamber 7. Thus, the inorganic flocculant solution can be directly supplied to the sludge supplied into the sludge supply chamber 7 (pre-stage supply in the inorganic machine). It is configured to be reinjected (inorganic post-stage injection) into the pool 10 (separated sludge scraped up by the screw blade 4c on the water surface WL of the pool 10) from the discharge hole 23a through the flocculant outlet 7b. The molecular flocculant supply pipe 16 supplies the polymer flocculant solution from the polymer flocculant discharge port 16b to the pool 10 (flocculated sludge flowing out from the sludge supply port 7a to the pool 10) through the flocculant outlet 7e (high It has become the child the middle supply) can be configured. The inorganic flocculant supply pipe 20 and the inorganic flocculant injection pipe 23 can be washed with water supplied from the branch water supply pipe 26b, and the inorganic flocculant solution injected from the inorganic flocculant injection pipe 23 is supplied with the water supply branch pipe. It can be diluted with feed water from 26a.

According to the sixth embodiment described above, the sludge supply chamber 7 rotating rapidly is performed by supplying the inorganic flocculant upstream and the polymer flocculant in the sludge supply chamber 7 of the centrifuge 1. The sludge and the inorganic flocculant supplied in the previous stage are mixed, and the generated flocculent sludge flows out to the pool 10 through the sludge supply port 7a, and the polymer flocculant flowing out from the flocculant outlet 7e there Supplied and becomes a solid agglomerated sludge with high solid-liquid separation.
On the other hand, when an inorganic flocculant and a polymer flocculant are supplied to the sludge supply pipe 14 (line supply), agglomeration flock (aggregated sludge) is generated in the sludge supply pipe 14, but this agglomerated sludge is supplied as sludge. It will repeatedly collide with the wall surface etc. through the inflow into the chamber 7 and the outflow from the sludge supply port 7a, which may cause the disintegration (destruction) of the flocs flocs and lead to a decrease in solid-liquid separation, but the sludge supply chamber 7 By supplying the inorganic flocculant and the polymer flocculant to the front (supplying the first stage of the inorganic machine / supplying the middle stage of the polymer), it is possible to reliably suppress the disassembly of the flocs.

  In this way, the solid-liquid separability of the coagulated sludge is increased by the pre-stage supply in the inorganic machine, the middle stage supply of the polymer, and the inorganic post-stage injection, and the clarification of the dehydrated separation liquid is increased (SS recovery rate is improved). The supply can reliably remove phosphorus (eutrophication substance) from the dehydrated separation liquid, and in addition, the water content can be drastically reduced by re-injecting the inorganic flocculant in the latter stage (post-injection). it can. In addition, since the inorganic flocculant system that easily adheres and solidifies can be reliably washed with the above-described configuration, the centrifuge 1 can be stably operated.

  Here, in more detail based on FIG. 7, sludge is supplied to the vicinity of the sludge supply port 7 a from the sludge supply pipe opening 14 a of the sludge supply pipe 14 extending into the sludge supply chamber 7, and the sludge supply pipe 14. The inorganic flocculant is supplied upstream from the inorganic flocculant supply pipe opening 20 a of the inorganic flocculant supply pipe 20 that is extended and disposed therein, and the sludge and the inorganic flocculant are first mixed in the sludge supply chamber 7. Then, the polymer flocculant is fed from the polymer flocculant discharge port 16b opened on the side surface of the polymer flocculant supply pipe 16 extended and disposed in the sludge supply pipe 14 to the partition plate 8d provided in the straight body portion 4a. The middle stage is supplied to the pool 10 (aggregated sludge flowing out from the sludge supply port 7a to the pool 10) through the coagulant outlet 7e opened in the vicinity, and the aggregated sludge and the polymer coagulant are mixed. Next, the inorganic flocculant is opened in the vicinity of the partition plate 8 provided in the inner body taper 4b from the inorganic flocculant discharge hole 23a opened in the side surface of the inorganic flocculant injection pipe 23 extended and disposed in the sludge supply pipe 14. Then, it is injected into the pool 10 (separated sludge scraped up by the screw blade 4c on the water surface WL of the pool 10) through the flocculant outlet 7b, and the separated sludge and the inorganic flocculant mix.

  By configuring the inside of the centrifuge 1 in this way, it is possible to supply and inject the inorganic flocculant and the polymer flocculent accurately and efficiently to the sludge, and to suppress the breakage of the flocculent flocs. Liquid separation performance is demonstrated, the water content of dehydrated sludge can be further reduced, and the amount of chemicals used can be reduced (saved). In the sixth embodiment, the inorganic flocculant supply pipe 20, the polymer flocculant supply pipe 16, and the inorganic flocculant injection pipe 23 are extended and disposed in the sludge supply pipe 14 (for example, as shown in FIG. However, the present invention is not limited to this, and each pipe is separately extended into the sludge supply chamber 7. Any structure can be used as long as each flocculant can be supplied and injected smoothly.

Embodiment 7 FIG.
FIG. 8 is a cross-sectional view showing a centrifugal separator according to Embodiment 7 of the present invention. The same components as those in FIGS.
In the sixth embodiment shown in FIGS. 6 and 7, the inorganic flocculant supply pipe 20 is extended to the sludge supply chamber 7, and the preceding supply of the inorganic flocculant is performed in the sludge supply chamber 7. In the form 7, the inorganic flocculant supply pipe 20 is connected to the sludge supply pipe 14 in order to sufficiently react the sludge and the inorganic flocculant supplied in the previous stage, and the inorganic flocculant is supplied to the sludge in the sludge supply pipe 14 in the previous stage ( Line supply). By configuring in this way, the sludge and the inorganic flocculant supplied in the previous stage are sufficiently mixed, and it is possible to reliably produce agglomeration flocs, and the phosphorus contained in the sludge is made into an insoluble salt, so that the phosphorus concentration of the separation liquid Can also be reduced. The connecting position of the inorganic flocculant supply pipe 20 to the sludge supply pipe 14 may be any place between the sludge storage tank 11 and the centrifuge 1.

Embodiment 8 FIG.
9 is a cross-sectional view showing a centrifugal separator according to an eighth embodiment of the present invention, FIG. 10 is an enlarged cross-sectional view showing the main part of FIG. 9, and the same components as those in FIGS. The duplicate explanation is omitted.
In the eighth embodiment, the partition plate 8d and the flocculant outlet 7e provided in the straight body portion 4a of the sludge supply chamber 7 in the centrifugal separator of the sixth embodiment (FIG. 6) are omitted, and the sludge supply pipe is omitted. In this structure, the gap between the opening 14a and the sludge supply port 7a is widened. Further, the water supply pipe 26 is not branched as in FIG. 2A and is connected to the inorganic flocculant injection pipe 23.
By adopting such a configuration, the structure in the sludge supply chamber 7 can be simplified while obtaining the same effects as those of the sixth embodiment shown in FIG. In addition, maintenance and maintenance work can be reduced.

  Referring to FIGS. 9 and 10, the eighth embodiment of the present invention will be described in detail. Sludge is supplied from the sludge supply pipe opening 14a of the sludge supply pipe 14 extending into the sludge supply chamber 7 toward the sludge supply port 7a. In addition, the inorganic flocculant is also supplied upstream from the inorganic flocculant supply pipe opening 20a of the inorganic flocculant supply pipe 20 extended in the sludge supply pipe 14 in the direction of the sludge supply port 7a. Sludge and inorganic flocculant are mixed first. Then, the polymer flocculant is discharged toward the inner wall of the sludge supply chamber 7 from the polymer flocculant discharge port 16b opened on the side surface of the polymer flocculant supply pipe 16 extended in the sludge supply pipe 14 (middle supply). ) And flows out from the sludge supply port 7a to the pool 10 mainly through this inner wall. The polymer flocculant supplied in the middle stage is mixed with sludge (flocculated sludge) in the pool 10 from the sludge supply chamber 7. Next, the inorganic flocculant from the inorganic flocculant discharge hole 23a opened on the side surface of the inorganic flocculant injection pipe 23 extended and disposed in the sludge supply pipe 14 is in the vicinity of the partition plate 8 provided in the inner trunk taper 4b. It is injected into the pool 10 (separated sludge scraped up by the screw blade 4c on the water surface WL of the pool 10) through the opening flocculant outlet 7b, and the separated sludge and the inorganic flocculant are mixed.

  In this way, the polymer flocculant can be mixed with the agglomerated sludge produced by mixing the sludge and the inorganic flocculant supplied in the previous stage, so that it is quick and efficient despite the simple structure. Strong cohesive floc can be formed. The coagulated sludge is subjected to solid centrifugal separation by receiving a strong centrifugal force in the pool 10, and an inorganic coagulant is injected into the separated sludge scraped up by the screw blade 4 c on the water surface WL of the pool 10, and further the solid-liquid separation is performed. move on.

  By configuring the inside of the centrifuge 1 in this way, the inorganic flocculant and the polymer flocculant can be supplied and injected accurately and efficiently into the sludge, as in the sixth embodiment. Destruction can be suppressed, good solid-liquid separation performance can be demonstrated, the moisture content of dewatered sludge can be further reduced, the amount of chemicals used can be reduced, and the structure in the sludge supply chamber 7 can be simplified. Can do. In addition, it is preferable that the shape of the sludge supply chamber 7 is provided with an inclination (narrowed) toward the separated discharge side as a whole. Further, the polymer flocculant discharge port 16b is opened on the side surface of the polymer flocculant supply pipe 16, but the present invention is not limited to this, and the polymer flocculant discharge port 16b may be discharged in the direction of the sludge supply port 7a. Any structure that can supply the polymer flocculant to the sludge in the middle stage may be used.

Embodiment 9 FIG.
FIG. 11 is a cross-sectional view showing a centrifugal separator according to Embodiment 9 of the present invention. The same components as those in FIGS.
In Embodiment 8 shown in FIG. 9 and FIG. 10, the inorganic flocculant supply pipe 20 is extended to the sludge supply chamber 7 and the upstream supply of the inorganic flocculant is performed in the sludge supply chamber 7. In order to sufficiently react with the inorganic flocculant supplied in the previous stage, the inorganic flocculant supply pipe 20 is connected to the sludge supply pipe 14, and the inorganic flocculant is supplied to the sludge in the sludge supply pipe 14 in the previous stage (line supply). . By configuring in this way, the sludge and the inorganic flocculant supplied in the previous stage are sufficiently mixed, and it is possible to reliably produce agglomeration flocs, and the phosphorus contained in the sludge is made into an insoluble salt, so that the phosphorus concentration of the separation liquid Can also be reduced. The connecting position of the inorganic flocculant supply pipe 20 to the sludge supply pipe 14 may be any place between the sludge storage tank 11 and the centrifuge 1. By adopting such a configuration, the structure in the sludge supply chamber 7 can be simplified while obtaining the same effects as those of the seventh embodiment shown in FIG. 8, and the manufacture of the apparatus is facilitated. In addition, maintenance and maintenance work can be reduced.

Embodiment 10 FIG.
FIG. 12 is a sectional view showing a centrifugal separator according to Embodiment 10 of the present invention. The same components as those in FIG.
In the tenth embodiment, the polymer flocculant supply pipe 16 connected to the sludge supply pipe 4 is provided with a branch pipe 16a, and the branch pipe 16a is provided with an on-off valve 19a. The point that the structure is switched to line supply or / and in-machine supply is greatly different from that of the third embodiment (FIG. 3). Both polymer flocculant supply systems using the polymer flocculant supply pipe 16 and the branch pipe 16a have characteristics, and are selected as appropriate depending on the type of polymer flocculant used and the reactivity with sludge. Basically, in the case of a polymer coagulant with high viscosity, reaction time with sludge is required, so it is preferable to supply the line, and supply in the machine when you want to keep the chemical injection rate low (e.g. when economy is a priority). Is preferred.

  In the case of the in-polymer supply system, it is preferable to extend two pipes, a polymer flocculant supply pipe 16 and an inorganic flocculant injection pipe 23, into the sludge supply pipe 14. Structural examples are shown in FIGS. As shown in FIG. 13, a structure in which the polymer flocculant supply pipe 16 and the inorganic flocculant injection pipe 23 are inserted into the pipe-shaped sludge supply pipe 14 may be adopted, and a double pipe structure is adopted as shown in FIG. A structure in which the outer pipe is partitioned may be used, and any structure may be used as long as it can be separated from sludge and supplied and injected with each coagulant.

  In this manner, the polymer flocculant supply pipe 16 and the inorganic flocculant injection pipe 23 (also the inorganic flocculant supply pipe 20 in the sixth and seventh embodiments) are extended inside the sludge supply pipe 14 that is essential for the centrifugal separator. By disposing, the structure of the bearings and seals of the inner cylinder screw 4 is not complicated, and by adopting a double pipe structure that partitions the inside of the sludge supply pipe 14, the sludge supply pipe 14 is provided inside. Since there is no foreign matter, the inside of the tube is easy to clean, and problems such as blockage can be avoided. When it is desired to supply the polymer flocculant extensively in the sludge supply chamber 7, the tip of the polymer flocculant supply pipe 16 is sealed as the double pipe structure (FIG. 14), and the vicinity of the vicinity of the pipe tip is used. A plurality of polymer flocculant discharge ports 16b may be provided at the same, whereby the polymer flocculant can be supplied in multiple directions.

Embodiment 11 FIG.
FIG. 15 is a cross-sectional view showing a centrifugal separator according to an eleventh embodiment of the present invention. Components identical or corresponding to those in FIGS.
In the eleventh embodiment, a phosphorus concentration measuring device 31 that measures the phosphorus concentration of the separation liquid discharged from the centrifugal dehydrator 1 and a phosphorus concentration measurement value signal from the phosphorus concentration measuring device 31 are input to supply an inorganic flocculant. The controller 21 is configured to control the pump 21 and the inorganic flocculant injection pump 24. By using the controller 30, the inorganic flocculant supply pump 21 (front-stage supply pump) and the inorganic flocculant injection pump 24 (rear-stage injection pump) are used. ) To control the flow rate.

  Usually, the phosphorus concentration in the separation liquid decreases in proportion to the supply / injection rate (amount) of the inorganic flocculant when the sludge concentration and the operating conditions of the dehydrator are the same. That is, the phosphorus component contained in the sludge can be reacted with the inorganic flocculant to be converted into an insoluble salt and removed together with the separated product, so that the phosphorus concentration of the separation liquid is lowered. From this, it is possible to accurately adjust the phosphorus concentration in the separation liquid by controlling the supply and injection of the inorganic flocculant while checking the phosphorus concentration in the separation liquid, in particular, the amount supplied by the inorganic flocculant supply pump 21 (stable Can be reduced).

  The phosphorus concentration measuring device 31 may be a phosphorus concentration automatic measuring device 31, measurement by manual analysis, or simple analysis by pack test or the like. The controller 30 can increase or decrease the output of the inorganic flocculant supply pump 21 or the like based on the measured phosphorus concentration value (output signal) (inverter), or can manually adjust the inorganic flocculant supply pump 21 or the like from the analysis result of the phosphorus concentration. Any flow rate can be used as long as the flow rate can be increased or decreased. In the eleventh embodiment, in order to reliably react the sludge and the inorganic flocculant, the pre-stage inorganic flocculant storage tank 13A is provided as in the fifth embodiment shown in FIG. The inorganic flocculant storage tank 13A is extended to the sludge storage tank 11 so that the inorganic flocculant can be supplied to the sludge storage tank 11, but is not limited thereto, and the sludge and the inorganic flocculant are sufficiently supplied. Any structure that can be mixed is acceptable.

  Moreover, although it is an indirect control regarding supply / injection control of an inorganic flocculant, it is also possible to use a pH meter. In the example using the digested sludge shown in Table 1, the relationship between the phosphorus concentration of the separation liquid and the separation liquid pH with respect to the supply rate (polyiron injection rate) of the inorganic flocculant in the previous stage is shown in FIG. When the polyiron injection rate is increased, the phosphorus concentration of the separation liquid is lowered and the pH is also lowered. This correlation may be confirmed periodically, and the phosphorus concentration of the separation liquid may be estimated from the pH value of the separation liquid to control the inorganic flocculant supply pump 21 and the like.

  The phosphorus concentration measuring device 31 and the controller 30 in the eleventh embodiment described above can also be applied to the centrifuges in the first to tenth embodiments, and the application of the centrifuges in the first to tenth embodiments by application thereof. The flow rates of the inorganic flocculant supply pump 21 and the inorganic flocculant injection pump 24 in the separator can be appropriately controlled.

Embodiment 12 FIG.
FIG. 16 is a sectional view showing a centrifugal separator according to a twelfth embodiment of the present invention.
In the twelfth embodiment, the controller 30A adjusts the ratio and flow rate of the inorganic flocculant before and after the injection by the on-off valves 32 and 33 and the like. By adopting such a configuration, the inorganic flocculant supply pump and the inorganic flocculant injection pump can be used together, and the initial cost can be reduced and the space can be saved. For the purpose of removing phosphorus from the separation liquid, the controller 30A measures the concentration of phosphorus in the sludge and the separation liquid and the pH of the separation liquid as described above, and outputs the on / off valves 32 and 33 according to the output signal. For the purpose of controlling the opening / closing and opening, and for the purpose of reducing the moisture content of dewatered sludge, measure the sludge amount (treatment amount), the moisture content and viscosity of the dewatered sludge, and use the output signal to open and close the valve. For control of opening and closing and opening of 32 and 33, and for the purpose of improving the SS recovery rate, measure the SS concentration, transparency, light transmittance, etc. of the separation liquid, and open / close by the output signal What can control the opening and closing and the opening degree of the valves 32 and 33 can be used. For example, when removing phosphorus from the separation liquid, if the phosphorus concentration in the sludge is low, the upstream supply amount of the inorganic flocculant is reduced and the subsequent injection amount is increased.

Embodiment 13 FIG.
FIG. 17 is a sectional view showing a centrifugal separator according to Embodiment 13 of the present invention.
In the thirteenth embodiment, a part of the separation liquid discharged from the centrifuge 1 is supplied to the water supply pipe 26 via the separation liquid circulation pipe 34 and the separation liquid is reused. The separation liquid circulation pipe 34 is provided with a separation liquid circulation pump 35 and an on-off valve 36 for circulating the separation liquid.
For example, when the throughput of the centrifuge 1 is 5 m ³ / h, the washing water amount is usually 4 m ³ / h and the washing time takes about 10 to 15 minutes in the stopping process, but the separated liquid is circulated and used. Therefore, if the separation liquid circulation rate is 3 m ³ / h, the total amount of wash water supplied to the centrifuge 1 is 7 m ³ / h, and the amount of water flow in the centrifuge 1 ( The water flow rate) was increased and the cleaning efficiency was improved, so that cleaning was possible in about 5 minutes.

  Further, if the separation liquid is circulated during the operation of the centrifugal separator 1, it can be used for diluting the inorganic flocculant, and when the inorganic flocculant is injected later, the inorganic flocculant diluted in the pool 10 is quickly recovered. Evenly distributed to the separated sludge and mixed, and good dewatering performance (low water content of the dewatered sludge) can be obtained.

  Further, the advantage of using the separated liquid for dilution is that the separated liquid is separated from sludge and has similar properties to sludge, so that the pH of the diluted inorganic flocculant to be injected later is appropriately maintained (acidic Can be suppressed). Normally, the optimum pH of polyiron, etc. is about 5-6 at the time of aggregation. For example, when using groundwater (well water) etc., the pH of groundwater is usually low and the pH of polyiron is also low. Deviation (lower pH) may occur, and new pH adjustment is required. On the other hand, the pH of the separated liquid is as high as about 8 in the case of digested sludge dehydration, for example, and even if the inorganic flocculant is diluted by circulating the separated liquid, the pH hardly fluctuates and is stably dehydrated. Can be done. In addition, since the separation liquid is usually centrifuged with a high centrifugal effect of 2000G or higher, and the water quality is also good (SS low concentration), even if the separation liquid is recycled to dilute the inorganic flocculant, the separation liquid There is almost no influence on the water quality (the use of diluted water that does not have a favorable water quality, such as a mixture of many fine particles, may deteriorate the water quality of the separated liquid).

Embodiment 14 FIG.
FIG. 18 is a cross-sectional view showing a centrifugal separator according to Embodiment 14 of the present invention.
In the fourteenth embodiment, as in the sixth embodiment (FIG. 6), the water supply pipe is branched and the branch pipes 26a and 26b are connected to the inorganic flocculant supply pipe 20 and the inorganic flocculant injection pipe 23. In addition, it is possible to wash the upstream supply system and the subsequent injection system of the inorganic flocculant. Thereby, since the inorganic flocculant system which is easy to adhere and solidify is reliably washed, the centrifuge can be operated stably, and when the separated liquid is circulated, running costs such as water bills can be reduced. Although not shown, scale (calcium) is generated in the water supply pipe 26 and the like due to long-term use, and the inorganic flocculant injection pipe 23, inorganic flocculant discharge holes 23a, 23b, 23c, flocculant outlets 7b, 7c, Since clogging (stenosis) such as 7d and 7e may occur, it is preferable to provide an acid cleaning facility.

It is sectional drawing which shows the centrifuge apparatus by Embodiment 1 of this invention. It is a schematic sectional drawing which expands and shows the principal part of FIG. It is sectional drawing which shows the centrifuge apparatus by Embodiment 2 of this invention. It is a schematic sectional drawing which expands and shows the principal part of FIG. It is sectional drawing which shows the centrifuge apparatus by Embodiment 3 of this invention. It is sectional drawing which shows the centrifuge apparatus by Embodiment 4 of this invention. It is sectional drawing which shows the centrifuge apparatus by Embodiment 5 of this invention. It is sectional drawing which shows the centrifuge apparatus by Embodiment 6 of this invention. It is sectional drawing which expands and shows the principal part of FIG. It is sectional drawing which shows the centrifuge apparatus by Embodiment 7 of this invention. It is sectional drawing which shows the centrifuge apparatus by Embodiment 8 of this invention. It is sectional drawing which expands and shows the principal part of FIG. It is sectional drawing which shows the centrifuge apparatus by Embodiment 9 of this invention. It is sectional drawing which shows the centrifuge apparatus by Embodiment 10 of this invention. FIG. 13A is an explanatory view showing a piping structure of a sludge supply pipe, a polymer flocculant supply pipe, and an inorganic flocculant injection pipe, and FIG. 13B is an end view of FIG. 13A. FIG. 14A shows a modified example of FIG. 13, and FIG. 14A is an explanatory view showing the piping structure of a sludge supply pipe, a polymer flocculant supply pipe, and an inorganic flocculant injection pipe, and FIG. ) Is an end view of FIG. It is sectional drawing which shows the centrifuge apparatus by Embodiment 11 of this invention. It is sectional drawing which shows the centrifugal separator by Embodiment 12 of this invention. It is sectional drawing which shows the centrifuge apparatus by Embodiment 13 of this invention. It is sectional drawing which shows the centrifuge apparatus by Embodiment 14 of this invention. It is a figure which shows the relationship between the phosphorus concentration of a separation liquid with respect to a polyiron injection rate, and the pH of a separation liquid.

DESCRIPTION OF SYMBOLS 1 Centrifugal machine 2 Casing 2a Separation liquid discharge port 2b Separation product discharge port 3 Outer body bowl 3a Straight body part 3b, 3c Two-stage taper 3d First-stage taper 4 Inner body screw 4a Straight body part 4b Inner body taper 4c Screw blade 5 , 6 Rotating drive 7 Sludge supply chamber 7a Sludge supply port 7b, 7c, 7d, 7e Coagulant outlet 8, 8a, 8b, 8c Partition plate 10 Pool 11 Sludge storage tank 12 Polymer flocculant storage tank 13 Inorganic flocculant Storage tank 13A Pre-stage inorganic flocculant storage tank 14 Sludge supply pipe 14a Sludge supply pipe opening 15 Sludge supply pump 16 Polymer flocculant supply pipe 16a Branch pipe 16b Polymer flocculant discharge port 17 Polymer flocculant supply pump 18 Flow meter 19 On-off valve 20 Inorganic flocculant supply pipe 20a Inorganic flocculant supply pipe opening 21 Inorganic flocculant supply pump 22 Flowmeter 23 Inorganic flocculant injection pipes 23a, 23b, 23c Inorganic flocculant discharge hole 24 Inorganic flocculant injection pump 25 Flow meter 26 Water supply pipe 26a, 26b Branch pipe 27 Automatic open / close valve 28 Water supply pump 30, 30A Controller 31 Phosphorus concentration measuring instrument 32, 33 Open / close valve 34 Separate liquid circulation pipe 35 Separating liquid circulation pump 36 On-off valve

Claims (4)

Sludge supplied through the sludge supply pipe
In a centrifuge for solid-liquid separation into a separated product and a separated liquid by a centrifuge equipped with an inner cylinder screw provided with an outer cylinder bowl and a sludge supply chamber ,
Supplying an inorganic flocculant to the sludge supply pipe,
Supplying the polymer flocculant to the sludge supply pipe and / or the sludge supply chamber;
further
An inorganic flocculant injection pipe for connecting the water supply pipe and injecting an inorganic flocculant into the sludge supply chamber is disposed in the inner cylinder screw, and the flocculant provided in the sludge supply chamber from the inorganic flocculant injection pipe A centrifugal separator characterized by injecting an inorganic flocculant into separated sludge that is scraped up to the separated product discharge side through an outlet . The centrifuge according to claim 1, wherein a partition plate is provided in the sludge supply chamber. The centrifuge according to claim 1, further comprising a phosphorus concentration measuring device that measures a phosphorus concentration of the separation liquid. The centrifuge according to any one of claims 1 to 3, further comprising a separation liquid circulation pipe that supplies the separation liquid to the water supply pipe.

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