RU2553100C2 - Gravity-magnetic separator - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to gravity-magnetic separator for flocculation of plankton and bacteria contained in ballast water and to separation of flakes collected by magnetic force. This separator comprises first tank with mixer connected with outboard water feed pipe to mix said water with added flocculating agent and magnetic powder. The latter is fed from appropriate device to make magnetic micro flakes including magnetic powder. Second tank comprises mixer for slower mixing of water whereto polymer flocculating agent is added. This allows the increase in sizes of magnetic micro flakes for processed water discharged from first tank with mixer. Magnetic separator serves to collect increased magnetic flakes by magnetic force. Said processed water is discharged from second tank with mixer and includes increased magnetic flakes. Return and addition device returns collected flakes from magnetic separator by scrapers into outboard water feed pipe to position ahead the first tank with mixer and ahead of position where flocculating agent is added to add collected flakes to outboard water.

EFFECT: higher efficiency of flocculation with no use of chemicals.

5 cl, 7 dwg, 2 tbl

Description

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The present invention relates to a flocculation magnetic separator for flocculation of plankton and bacteria contained in ballast water, and to the separation of flakes thus collected by magnetic force.

Description of the Prior Art

In accordance with the International Convention for Control and Management of Ship's Ballast Water, adopted by the International Maritime Organization (IMO) in 2004, ships must be equipped with a system to remove or sterilize plankton and bacteria contained in ballast water. This convention was adopted with the aim of preventing the movement of microorganisms using ballast water (or sea water), the destruction of the ecosystem through the spread of microorganisms and the health risks caused by microorganisms.

Currently, ballast water treatment technologies are being actively developed by combining a variety of water treatment technologies, including chimeric processing using sodium hypochlorite or the like, ozonation, ultraviolet radiation, heat treatment and magnetic separation or the like.

Here, the flocculation magnetic separator described in Patent Document 1 operates by the steps of: adding magnetic powder and flocculant to ballast water (or sea water); mixing the resulting mixture with the formation of magnetic flakes containing microorganisms and bacteria mixed in ballast water; separating magnetic flakes from ballast water using a magnetic separation device and collecting relatively large solid materials that are not able to flocculate on their own (for example, small fish, each a few millimeters in size, and seaweed) using a drum filter.

When the flocculation magnetic separator is operating, the flocculant used is a very safe agent, which is also used to treat tap water. In addition, this treatment of water using a flocculant is less risky than treatment using a chemical such as chlorine. In other words, flocculation treatment is less prone to secondary environmental pollution by chemicals remaining in ballast water at the time of release and related by-products.

In addition, the flocculation magnetic separator flocculates not only microorganisms and bacteria, but also sand and sludge in ballast water, thereby simultaneously separating and removing all materials. This allows the flocculation magnetic separator to have a secondary effect of preventing the accumulation of sand and silt in the lower part of the ballast tank.

However, there are the following problems encountered in the flocculation magnetic separator described in Patent Document 1. One of the problems is that the amounts of expensive magnetic powder used must be reduced while maintaining the performance of ballast water treatment. Another problem is that the total amount of flakes collected must be reduced.

Namely, with respect to the flocculation magnetic separator, the magnetic powder thus added should be kept as uniform in all the flakes as much as possible when magnetic flakes are formed. In this case, a magnetic powder should be used, consisting of particles, each of which has an extremely small particle size of several microns, as well as the same particle size.

However, it should be noted that such a magnetic powder is very expensive, which leads to an increase in the cost of the flocculation magnetic separator. For this reason, it is necessary to reduce the amount of magnetic powder used as much as possible. In addition, assuming that the flocculation magnetic separator is mounted on the ship, reducing the amount of magnetic powder makes it possible to reduce the size of the storage tank for the magnetic powder.

This provides a great advantage when installing a flocculation magnetic separator inside the vessel, which has limited space for accommodating various devices. At the same time, this advantage allows to reduce the frequency of operations for feeding magnetic powder into the vessel, which reduces the load on sailors.

Meanwhile, the collected flakes discharged from the magnetic separator should be stored in a tank and treated as industrial waste. Thus, there is an urgent need for the collected flakes to be recycled as much as possible to reduce their total quantity so as to reduce the size of the storage tank, to save space and reduce the cost of processing industrial waste.

From the point of view of what has been discussed above, it should be noted that Patent Document 2 describes a magnetic separation treatment device having the following feature. That is, the magnetic separation treatment device operates by performing the steps of: adding hydrochloric acid to the collected flakes while stirring the mixture; decomposition of the polymer flocculant, which must be separated into a decomposed flocculant, which contains oil and treated water, and a component of magnetic powder; and returning the decomposed flocculant and magnetic powder to sea water to recycle these materials.

Background Documents

Patent documents

Patent Document 1: JP H09-117618

Patent Document 2: JP 2006-718

Disclosure of invention

Problems to be Solved by the Invention

In Patent Document 2, hydrochloric acid is used to recycle magnetic powder. It should be noted here that the use of hydrochloric acid on a ship requires the submission of documents for verification of IMO; The documents demonstrate the safety of the installation of a treatment system using hydrochloric acid, i.e. strong acid. In addition, additional documents must be submitted to verify the IMO; documents demonstrate the reliability of the method of neutralizing processed materials.

Accordingly, such extremely complex procedures are necessary to use such a treatment system that uses hydrochloric acid.

Because of the circumstances, as described above, the development of a flocculation magnetic separator is required that can reduce the amount of flakes collected as well as the amount of magnetic powder used; the flocculation magnetic separator should be able to physically remove microorganisms and bacteria contained in ballast water, as described in patent document 1.

Here, the problem associated with the method of reducing the quantities of magnetic powder used and the quantities of flakes collected without using a chemical such as hydrochloric acid to treat seawater is not limited to the case of ballast water treatment. The same problem arises in the case of sea water, which is treated on shore.

The present invention has been developed in light of the problems described above. For this reason, it is an object of the present invention to provide a flocculation magnetic separator capable of reducing the amount of magnetic powder used without using chemicals such as hydrochloric acid, as well as the amount of collected flakes, for treating overboard water.

Problem Solving Tools

Accordingly, the present invention is implemented to achieve the above objectives. That is, a flocculation magnetic separator is proposed comprising: a first reservoir with a stirrer for forming magnetic micro flakes containing magnetic powder; and a second reservoir with a stirrer for increasing the size of the magnetic micro flakes by mixing the water to be treated, to which the polymer flocculant is added.

Here, the first agitator tank is connected to the overboard water supply pipe and magnetic micro flakes are formed by rapidly mixing the overboard water to which magnetic powder and flocculant are added. Such magnetic powder is supplied from the magnetic powder supply device. In addition, the seawater to be treated in the second agitator tank contains magnetic micro flakes discharged from the first agitator tank. The second tank is mixed at a lower rotational speed than the first tank.

In addition, the flocculation magnetic separator comprises: a magnetic separation device for collecting oversized flakes by magnetic force, and a return and addition device for returning flakes thus collected by the magnetic separation device into a seawater supply pipe positioned in front of the first a tank with a stirrer and in front of the position where a flocculant is added to seawater. The return and refill device then adds the collected flakes to the seawater.

Here, the flocculation magnetic separator of the present invention includes a return and refill device for returning flakes discharged from the magnetic separation device to a seawater supply pipe in a position in front of the first agitator tank and before the position where the flocculant is added. Collected flakes unloaded from the magnetic separation device are stored once in a collection tank for collected flakes. Then the collected flakes are returned to the pipe for supplying sea water using a return and addition device.

Accordingly, the magnetic powder contained in the collected flakes is recycled according to the present invention. This recycling method makes it possible to reduce the amounts of magnetic powder used without using chemicals such as hydrochloric acid or the like, and in addition, the amount of collected flakes should be reduced. In addition, this method of recycling makes it unnecessary to complex separation and processing of magnetic powder for separation. It should be noted that the collected flakes that are not returned are given the opportunity to flow from the collection tank for the collected flakes as an excess of collected flakes so that they are stored separately in the storage tank for the collected flakes.

The flocculation magnetic separator of the present invention preferably comprises a concentration detecting device for detecting the concentration of suspended solids in seawater in front of positions where magnetic powder, flocculant and collected flakes are added.

In addition, the flocculation magnetic separator preferably comprises a control device for monitoring the returned amounts of flakes collected by the return and addition device, together with the amounts of magnetic powder added by the magnetic powder supply device.

Here, the control device performs the above operation based on both the concentration of suspended solids detected by the concentration detection device and the maximum concentration of suspended solids in seawater set in advance.

The control device of the present invention controls the amount of collected flakes returned by the return and addition device, and the amounts of magnetic powder added by the magnetic powder supply device.

Here, the control unit performs an operation based on both the concentration of suspended solid products detected by the concentration detecting device and the maximum concentration of suspended solid products in seawater set in advance (or the calculated value for the flocculation magnetic separator).

According to the present invention, a concentration of suspended solid products in seawater is detected, and then it is confirmed that the detected concentration is lower than a maximum concentration of suspended solid products in seawater. This procedure eliminates complex processing for separation and recovery, and for this reason, the collected flakes are recycled using a simple and inexpensive system structure. In addition, the method of recycling the magnetic powder contained in the collected flakes makes it possible to reduce the amounts used of a completely new magnetic powder. It also becomes possible to further reduce the generated amounts of collected flakes obtained from a completely new magnetic powder.

In addition, in accordance with the present invention, if the concentration of suspended solids detected by the concentration detection apparatus is determined to be equal to the maximum concentration of suspended solids in seawater, the control device preferably stops the return process of the collected flakes carried out by the return and addition device. At the same time, the control device preferably controls the amounts of magnetic powder added by the magnetic powder supply device, while increasing the amount of collected flakes returned by the return and addition device when the concentration of suspended solids becomes lower than the maximum concentration of suspended solids in seawater. In addition, the control device preferably controls the amounts of magnetic powder added by the magnetic powder supply device, so that the amounts added are to be reduced.

Accordingly, the above procedure of the present invention makes it possible to more stable processing performance for a flocculation magnetic separator, regardless of the concentration of suspended solids in seawater.

At the same time, in accordance with the present invention, if the concentration of suspended solids in seawater becomes higher than the maximum concentration of suspended solids in seawater, the collected flakes cannot be returned to the seawater supply pipe. However, in order to return the collected flakes in order to recycle the magnetic powder contained in the collected flakes even in the case mentioned above, the return method should extract only the component of the magnetic powder from the collected flakes and remove other suspended solid components.

From the point of view of what is described above, in the present invention, the device for extracting magnetic powder is provided with a return pipe located between the return device and the addition and the supply pipe of sea water. A magnetic powder extraction device comprises: a grinding device for grinding collected flakes by shear; an extraction device for selectively extracting only magnetic powder from the collected flakes, thus crushed by magnetic force, and a return device for returning the extracted magnetic powder into the pipe for supplying sea water.

The magnetic powder extraction device of the present invention carries out the steps of: extracting the magnetic powder component from the collected flakes and removing other suspended solid components through the steps in two steps, as discussed below.

At the stages of the first stage, the collected flakes are crushed by applying physical force to them. It should be noted that the collected flakes are formed by strong flocculation of magnetic powder and other suspended solid components with an inorganic flocculant and a polymer flocculant. For this reason, the stage of grinding the product of strong flocculation is carried out using an ultrasonic grinder, a linear grinder or ball mill to grind the product of strong flocculation.

That is, the collected flakes are crushed using only physical effort without the use of chemicals such as hydrochloric acid. This makes it possible to reduce the risk arising at this stage associated with the leakage of chemical, providing at this stage a high safety characteristic. As a result, when the magnetic powder extraction unit is installed on the ship, this safety feature simplifies the installation approval process by IMO, it is simpler.

Then, in the stages of the second stage, the crushed flakes consisting of magnetic powder are removed from the original collected flakes using a magnetic force extraction device. Thus, other suspended solids are removed from the recovered flakes. Then, the recoverable collected flakes are returned to the seawater supply pipe using a return device.

It should be noted that suspended solid components other than magnetic powder are removed from the collected flakes, which must be returned. In this case, the collected flakes, consisting of magnetic powder, which must be returned, are very clean. Accordingly, the collected flakes can be returned to the seawater supply pipe even if the concentration of suspended solids in the seawater is high.

In the present invention, it is preferable to place a sterilization device for sterilizing plankton and bacteria contained in the collected flakes in the passage for returning the collected flakes. Here, the return process is carried out using the return and add device.

When the flocculation magnetic separator of the present invention is used in a ballast water treatment system mounted on a ship, the plankton and bacteria contained in the collected flakes are sterilized using a sterilization device. Then the collected flakes, sterilized in this way, are returned to the pipe for supplying sea water. This procedure can reduce the other load loaded on the seawater with the collected flakes.

Effect of the invention

The flocculation magnetic separator of the present invention makes it possible to reduce the quantities of magnetic powder used without the use of chemicals such as hydrochloric acid, and in addition, the amount of collected flakes is reduced.

Brief Description of the Drawings

Figure 1 is a diagram showing the overall construction of a flocculation magnetic separator in one embodiment.

Figure 2 is a block diagram showing the main part of a flocculation magnetic separator that does not contain a magnetic powder extraction unit. It should be noted that FIG. 1 shows a separator equipped with a magnetic powder extraction unit.

Figure 3 is a block diagram of a flocculation magnetic separator in figure 1.

FIG. 4 is a graph showing return fractions of collected flakes in a flocculation magnetic separator in FIG. 2.

FIG. 5 is a graph showing return fractions of collected flakes in a flocculation magnetic separator in FIG. 3.

6 is a graph showing the relationship between the concentration of added magnetic powder and the proportion of removal of flakes.

Fig. 7 is a graph showing the relationship between the concentration of SS (suspended solids) in sea water and the flake return ratio.

Embodiments of the present invention

Next, preferred embodiments of the flocculation magnetic separator of the present invention will be explained in detail with reference to the accompanying drawings.

Figure 1 is a diagram showing the overall design of the flocculation magnetic separator 10 in one embodiment. Flocculation magnetic separator 10 contains: a pipe 12 for supplying sea water; flocculation node 14; a magnetic separation unit 16 (or a magnetic separation device); node 18 return and add (or device return and add); a magnetic powder extraction unit 20 (or a magnetic powder extraction device); a thermal sterilization unit 22 (or a sterilization device) and a control unit 24 (or a control device).

It should be noted that the flocculation magnetic separator 10 in the present embodiment is used in a ballast water treatment system installed on a ship. In this case, the separator 10 is equipped with a node 22 thermal sterilization. However, when such a flocculation magnetic separator is located onshore, the thermal sterilization unit 22 is not an important component of the separator 10.

In addition, if the flakes collected by the magnetic separation unit 16 are directly returned to the pipe 12 for supplying sea water through the return and addition unit 18, the magnetic powder extraction unit 20 is also not an important component of the separator 10.

The flocculation unit 14 comprises a high speed agitating tank 26 (or a first agitator tank) and a low speed agitating tank 28 (or a second agitator tank). The flocculation unit 14 produces magnetic micro flakes from water to be treated (or seawater), which is supplied through a pipe 12 for supplying sea water. For this operation, the overboard water supply pipe 12 is provided with a magnetic powder supply unit 30 (or a magnetic powder supply device) and a flocculant adding unit 32. In addition, the polymer flocculant addition unit 36 is located on a pipe 34 through which water to be treated is supplied from the high-speed mixing tank 26 to the low-speed mixing tank 28.

The magnetic powder supply unit 30 has a pump 38 for injecting magnetic powder. The rotational speed of the magnetic powder injection pump 38 is controlled by the monitoring unit 24. This mechanism controls the added quantities of a completely new magnetic powder added to the pipe 12 for supplying sea water.

In addition, a concentration meter 40 of SS (suspended solids: hereinafter referred to as SS) (or a turbimeter) that detects the concentration of suspended solids is connected in front of the overhead water pipe 12. The SS concentration data detected by the SS concentration meter 40 is provided to the monitoring unit 24. Then, based on the concentration data of SS, the monitoring unit 24 controls the rotation speed of the pump 38 for injecting magnetic powder, as well as the rotation speed of the pump 42 for collecting collected flakes, which is a component of the return and addition unit 18.

Based on the above mechanism, a completely new magnetic powder and collected flakes are added to the seawater, which flows through the pipe 12 for supplying seawater. It should be noted here that the attachment position of the SS concentration meter 40 is not limited to the overboard water supply pipe 12. In this regard, any attachment position may be preferred provided that the attachment position is in the area in front of the area in which magnetic powder, flocculant and collected flakes are added. For example, an SS concentration meter 40 may be connected to a temporary storage tank for overboard water.

Here, as a magnetic powder, iron (II) ferrite powder can preferably be used. As the flocculant, a water-soluble inorganic flocculant, such as polyaluminium chloride, iron (III) chloride and iron (III) sulfate, can preferably be used. In addition, an anionic flocculant and a nonionic flocculant can preferably be used as the polymer flocculant.

The high-speed agitation tank 26 has a paddle mixer (not shown in FIG. 1) that rotates rapidly in order to agitate a mixture of overboard water, magnetic powder, flocculant and collected flakes that are added to the overboard water. Outboard water, to which magnetic powder, flocculant and collected flakes are added, is quickly mixed with a paddle mixer. This operation enables the formation of extremely small magnetic microflakes, which have a size of several tens of microns, in the tank 26 with high-speed mixing. When magnetic micro flakes form, microorganisms and bacteria in seawater are adsorbed on magnetic powder, which acts as an adsorption core, since microorganisms and bacteria are electrically charged, and they collect in magnetic micro flakes.

The low-speed agitating tank 28 is constructed as a multi-stage agitated tank, consisting of a series of multiple tanks. The tank with a mixer at each stage is equipped with a paddle mixer (not shown in figure 1). With respect to the tank 28 with a mixer constructed in a multi-stage form, the mixing speed of each tank is set so that the mixing speed decreases stepwise from the previous tank with the mixer to the next tank with the mixer. In this case, the water to be treated, together with the content of magnetic micro flakes and polymer flocculant, which are added to the water to be processed, all of them are supplied to the tank 28 with low-speed mixing from the tank 26 with high-speed mixing. As a result, the mixing speed decreases stepwise when moving from the previous tank with the mixer to the next tank.

This mechanism facilitates the growth of magnetic micro flakes, while they become larger flakes. In addition, since the mixing speed in each tank decreases stepwise, there is only a small chance that oversized flakes will be destroyed by the corresponding paddle mixers.

The magnetic separation unit 16 collects oversized flakes from the water to be treated, and it contains: a magnetic separation tank 44, a magnetic filter 46, a scraper (not shown in FIG. 1), and a conveyor system 48. Water to be treated containing oversized flakes are supplied from the reservoir 28 with low-speed mixing into the reservoir 44 of the magnetic separation. The magnetic filter 46 is, for example, in the form of a rotating drum, and at least a portion of the filter 46 is immersed in the water to be treated in the magnetic separation tank 44. In this case, the magnetic separation filter 46 collects larger flakes that drift in the magnetic separation tank 44 filled with water to be processed.

Then, oversized flakes so collected (or collected flakes) rise upward from the magnetic separation tank 44 due to the rotational movement of the magnetic filter 46. The raised oversized flakes are scraped off from the magnetic filter 46 using a scraper. Thereafter, the collected flakes thus scraped off are transferred to a collecting tank 50 for collecting flakes using a conveyor system 48, such as a screw conveyor. Collected flakes transported in this way are temporarily stored in tank 50.

The collected flakes stored in the collecting tank 50 for collected flakes are sent to the thermal sterilization unit 22 using a pump 42 to return the collected flakes. The thermal sterilization unit 22 sterilizes microorganisms and bacteria contained within the collected flakes by heat treatment of the collected flakes.

It should be noted that the collected flakes are in the form of a suspension. For this reason, it is preferable to use a positive displacement pump, such as a tubular pump, or a pump of the uniaxial screw type, as the pump 42 for returning the collected flakes. The heating temperature for sterilizing bacteria or the like is set in the range of 75 to 80 ° C, and the heating time is set in about three minutes.

At the same time, the magnetic powder extraction unit 20 comprises: grinding units 52 and 54 (or grinding devices) for grinding collected flakes by shear; an extraction unit 56 (or extraction device) for selectively extracting the magnetic powder component from the crushed collected flakes by magnetic force and a pump 58 (or return device) for returning the extracted magnetic powder component to the overhead water supply pipe 12.

As discussed above, the flocculation magnetic separator 10 shown in FIG. 1 is one embodiment in which the thermal sterilization unit 22 is positioned in front of the collecting flakes return passage, which is sent to the return and addition unit 18. In addition, in one embodiment, the magnetic powder extraction unit 20 is located in the position after the return passage.

The grinding unit 52 is a linear chopper that generates a strong shear force by rapidly rotating the blade mixer 60, which has a special shape. In contrast, the other grinding unit 54 is an ultrasonic shredder (frequency = about 20 kHz) that generates shear with the liquid 64 by immersing the vibrator 62 in the form of a rod vibrating with the frequency of the ultrasonic wave in the liquid 64.

It should be noted that in the present embodiment, two grinding units 52 and 54 are located, although one of these units may be installed. Alternatively, a ball mill 65 may be used as the grinding unit (or grinding device).

Then, the collected flakes, crushed using the nodes 52 and 54 grinding, are fed into the node 56 extraction. The extraction unit 56 retrieves the magnetic powder component from the crushed collected flakes using magnetic force. In such an extraction unit 56, in which a system using a magnetic disk or magnetic drum is used, permanent magnets are immersed in the disk and drum.

This design makes it possible to extract the magnetic powder component from the collected flakes, and SS substances other than the magnetic powder component must be released.

Here, the discharged content of substances SS other than the magnetic powder component is about 0.2% of the capacity of the flocculation magnetic separator 10. Accordingly, the extraction unit 56 in the present embodiment may be smaller than the magnetic separation unit 16, which is the main component.

The collected flakes, in which the extraction processing for extracting the magnetic powder component ends, are stored in the reservoir for collecting flakes (not shown in FIG. 1) as separated and collected flakes. This method is similar to the method carried out for excess collected flakes that are generated in the collecting tank 50 for collected flakes. It should be noted that the component of the magnetic powder, extracted using magnetic force, has a low water content, which leads to low fluidity. Moreover, the component of the magnetic powder is supplied to the reservoir 68 of the storage of pure water 66, while it is diluted in it. Thereafter, the component of the magnetic powder, thus diluted with pure water 66, is returned to the pipe 12 for supplying seawater using a pump 58. This method makes it possible to add magnetic powder of high purity to the water that must be processed and which flows through the pipe 12 for supplying overboard water.

Here, in the seawater supply pipe 12, the return position of the collected flakes and the position of adding magnetic powder are in the position after the SS concentration meter 40 and in the position in front of the high-speed mixing tank 26, and in the area in front of the position where the flocculant is added. It should be noted that the rotation speed of the pump 58 is controlled by the monitoring unit 24 on the basis of the SS concentration data measured using the SS concentration meter 40.

Next will be described in detail the effects of flocculation magnetic separator 10, designed as described above.

FIG. 2 is a block diagram showing the main part of the flocculation magnetic separator 10. This main part of the flocculation magnetic separator 10 is a separator constructed by removing the magnetic powder extraction unit 20 from the flocculation magnetic separator 10 shown in FIG. 1.

That is, the flocculation magnetic separator 10 in FIG. 2 is an embodiment in which only the thermal sterilization unit 22 is in the passage for returning collected flakes. Here, the return process is carried out using the node 18 return and add.

In the flocculation magnetic separator 10 in FIG. 2, a return and addition unit 18 is located, which returns and adds collected flakes withdrawn from the magnetic separation unit 16 to the area in front of the position where the flocculant is added in the overhead water supply pipe 12. The collected flakes withdrawn from the magnetic separation unit 16 are temporarily stored in a collection tank 50 for collected flakes (see FIG. 1). Then, the collected collected flakes are returned to the pipe 12 for supplying seawater using a pump 42 for returning the collected flakes included in the return and addition unit 18.

In contrast, the non-returned collected flakes are stored separately in the collected flakes storage tank (not shown in FIG. 2) by flowing the flakes from the collecting flakes receiving tank 50 as excess flakes.

As discussed above, the procedure for returning the collected flakes to the overboard water supply pipe 12 makes it possible to recycle the collected flakes without using a chemical such as hydrochloric acid. As a result, a component of the magnetic powder is contained in the collected flakes, making it possible to reduce the amounts used of a completely new magnetic powder. In addition, this also reduces the total amount of collected flakes generated in this way due to the addition of a completely new magnetic powder.

At the same time, the control unit 24 controls the amount of collected flakes returned by the return and addition unit 18, and the quantities of a completely new magnetic powder added by the magnetic powder supply unit 30. Here, this monitoring operation is carried out on the basis of the SS concentration detected by the SS concentration meter 40 and the maximum SS concentration in the sea water, where the maximum SS concentration in the sea water needs to be set in advance.

That is, when the SS concentration detected by the SS concentration meter 40 is equal to the maximum SS concentration in the seawater, the control unit 24 stops the collecting flakes return operation carried out by the return and addition unit 18. At the same time, the control unit 24 controls the quantities of a completely new magnetic powder added by the magnetic powder supply unit 30.

At this time, when the SS concentration becomes lower than the maximum SS concentration in the seawater, the control unit 24 increases the amount of collected flakes returned by the return and addition unit 18. At the same time, the control unit 24 reduces the amounts of a completely new magnetic powder added by the magnetic powder supply unit 30.

The above procedure makes it possible to stabilize the processing characteristics of the flocculation magnetic separator 10 in FIG. 2, which is independent of the concentration of SS in sea water. It should be noted that the node at 70 represents a filter. A filter 70 separates the treated water and the wash water from the water to be treated, which is separated by the magnetic separation unit 16. Then, the wash water is returned to the pipe 12 for supplying sea water through the pipe 72.

Next, a control method implemented by the monitoring unit 24 will be described in more detail in detail.

First, it should be noted that the returned amount of collected flakes is controlled by the rotation speed of the pump 40 to return the collected flakes, which is controlled by the control unit 24. Here, the share of collected flakes in returned quantities is set in the range from 0 to 100% of the total output of collected flakes.

Secondly, it should be noted that the returned amounts of collected flakes are monitored using a monitoring unit 24 based on the SS concentration in the seawater detected by the SS concentration meter 40, together with the maximum SS concentration in the seawater set in advance.

For example, it is assumed that the flocculation magnetic separator 10 is configured to have a maximum SS in sea water of 50 mg / L. In this case, it is believed that sea water having an SS concentration of 50 mg / L flows in the pipe 12 for supplying sea water. If 100% of the collected flakes is returned to sea water, this means that SS in amounts corresponding to an SS concentration of 50 mg / L is returned to sea water. Accordingly, the concentration of SS in seawater flowing into the tank 26 with high-speed stirring is represented by the following formula: 50 + 50 = 100 mg / L. Moreover, the SS concentration in sea water, having a value of 100 mg / l, is higher than the maximum SS concentration in sea water, corresponds to a negligible performance of the flocculation magnetic separator 10.

On the other hand, when seawater having an SS concentration of 10 mg / l flows into the seawater supply pipe 12, the flocculation magnetic separator 10 has sufficient processing capability to treat seawater to the extent that seawater can be treated with an SS concentration of 40 mg / l compared to seawater with a maximum SS concentration of 50 mg / l.

As a result, there is no problem of returning the amount of collected flakes corresponding to the remaining processing capacity for the flocculation magnetic separator 10.

In the test calculation, when the flocculation magnetic separator 10 in FIG. 2 is used for treatment of seawater, the ratio between the concentration of SS in the seawater (A) (mg / l), the returned amount of collected flakes (B) (return ratio (%) of the number of collected flakes in relation to the amount of flakes removed) and the added amount of a completely new magnetic powder (C) (mg / l) are shown in the graph in Fig. 4 and in table 1 below.

Here, the graph in FIG. 4 and table 1 show the return amount of flakes collected when the maximum estimated SS concentration in the seawater is 50 mg / L.

In the graph of FIG. 4, the vertical axis represents the fraction of magnetic powder contained in the flakes at a time before returning to the magnetic separation unit 16. The horizontal axis represents the proportion of returned flakes collected relative to the output.

In addition, the value of the lower limit of the proportion of magnetic powder in the flakes is set at 31.4%. Here, the proportion of returned flakes and the added amount of a completely new magnetic powder is set so that the proportion of magnetic powder becomes equal to 31.4% or more, for effective magnetic separation using the magnetic separation unit 16.

It should be noted that in the present embodiment, the share of the return of the flakes and the added amount of a completely new magnetic powder is set at 31.4%. More specifically, as shown in Table 1, when the SS concentration in sea water is 50 mg / L, the flocculation magnetic separator 10 does not return the collected flakes, while the separator 10 adds only a completely new magnetic powder at a concentration of 30 mg / L. The SS concentration in sea water is detected using an SS concentration meter 40, and the flocculation magnetic separator 10 controls the return fraction of the collected flakes and the added amount of a completely new magnetic powder corresponding to the detected data, measured in such a way as shown in Table 1.

In addition, when a flocculation magnetic separator 10 is used to treat ballast water, the maximum SS concentration in the seawater is set to be 50 mg / L, following IMO guidelines. However, since the actual concentration of SS in seawater often matters less than 10 mg / L, the process of returning the collected flakes to the seawater supply pipe 12, configured as discussed above, reduces the amount of brand new magnetic powder used.

It also makes it possible to reduce the stored required quantities of a completely new magnetic powder, which gives advantageous qualities for a vessel in which the internal space for accommodating a plurality of devices is substantially limited. It should be noted that plankton and bacteria (viable organisms) are chosen as a target for removal during processing of ballast water. For this reason, when the collected flakes are returned to the overboard water supply pipe 12, a thermal sterilization unit 22 is disposed in the return line to return collected flakes after sterilization of plankton and bacteria.

Table 1 A B C fifty 0 (do not return) thirty 40 16 26 thirty 31 21 twenty 47 16 10 62 12

On the other hand, the injected quantities of a completely new magnetic powder are controlled by the monitoring unit 24 by setting the rotation speed of the pump 38 for injecting the magnetic powder. Here, the control operation is carried out in the range from 0 to 100%, while the proportion of 100% (i.e. 30 mg / l), calculated in relation to the injected amount of a completely new magnetic powder, represents the case when the collected flakes do not return to the pipe 12 for feeding sea water. The injected amounts of a completely new magnetic powder are determined by the returned amounts of collected flakes. For example, when the return amount of collected flakes relative to the amount withdrawn is 47%, the magnetic powder that flows into the tank 26 with high-speed stirring should return 47% of it. In this case, the injected amounts of a completely new magnetic powder can be set at about 53% (or 16 mg / l).

The returned amount of collected flakes is detected using a flow meter 74, which is located in the pipe to return the collected flakes. Based on the measurement results of the flow meter 74, the control unit 24 controls the rotation speed of the pump 38, thereby setting the injected quantities of a completely new magnetic powder.

Here, the flocculation magnetic separator 10 in FIG. 2 cannot return the collected flakes if the SS concentration in the sea water is greater than the maximum calculated SS concentration in the sea water. For this reason, even in this case, in order to return the collected flakes in order to recycle the magnetic powder component in the collected flakes, in the return process it is necessary to remove only the magnetic powder component from the collected flakes and remove other SS components.

Next, the flocculation magnetic separator 10 in figure 3 shows the location of the nodes. Here, the magnetic powder extraction unit 20 is located in the position after the magnetic separation unit 16, and the thermal sterilization unit 22 is located in the position after the magnetic powder extraction unit 20.

That is, the flocculation magnetic separator 10 in FIG. 3 is an embodiment in which the magnetic powder extraction unit 20 is located in a position in front of the passage for returning the magnetic flakes; the return method is carried out using the return and addition unit 18, while the thermal sterilization unit 22 is located in the position after the return passage.

The magnetic powder extraction unit 20 separately processes the collected flakes that are released from the magnetic separation unit 16 in the following two steps from the steps: removing the magnetic powder component contained in the collected flakes and removing other SS components from the collected flakes.

The first stage includes the stages: grinding the collected flakes by applying physical effort to the collected flakes. In the collected flakes, the magnetic powder component and other SS components are strongly agglomerated by means of an inorganic flocculant and a polymer flocculant. Accordingly, a linear shredder 52 and / or an ultrasonic shredder 54 is used to grind such highly agglomerated flakes.

It should be noted that it has been experimentally determined that the collected flakes, firmly agglomerated in this way, decompose almost before grinding, by processing for grinding them for several tens of seconds to several minutes, carried out using a linear grinder 52 and / or ultrasonic grinder 54.

Here, a method of adjusting the pH value using a chemical as described in Patent Document 2 can be carried out in order to facilitate decomposition of the collected flakes. However, when processing is carried out on a ship, it is preferable to decompose the collected flakes by a physical method only, taking into account IMO instructions or the like.

The second stage includes the stages of: extracting only the component of the magnetic powder from the collected flakes, thus crushed by magnetic force. As the extraction unit 56 (see FIG. 1), a unit using a magnetic disk or a magnetic drum in which the permanent magnets are immersed can be used. Then the second stage further includes the steps of: diluting the extracted component of the magnetic powder with pure water 66 (see FIG. 1) and returning the component of the magnetic powder to the pipe 12 for supplying overboard water (see FIG. 1) using a pump 58 (see FIG. one).

During the two stages of these stages, the purity of the component of the magnetic powder to be returned is increased. This increase in purity makes it possible to return collected flakes containing the main component of the magnetic powder, even if the SS concentration in the seawater rises.

Here, a test calculation is carried out, assuming that the SS components other than the magnetic powder component are separated from 30% of the collected flakes. Accordingly, in the case of a flocculation magnetic separator 10 in FIG. 3, the ratio between the concentration of SS in seawater (A) (mg / l), the returned amounts of collected flakes (B) (it is represented by the percentage of return of collected flakes in relation to the displayed quantities of collected flakes) and the added quantities of a completely new magnetic powder (C ) (mg / l), presented using the graph in figure 5 and table 2.

The results mentioned above demonstrate that the flocculation magnetic separator 10 in FIG. 3 can further increase the return fraction of the collected flakes, the corresponding SS concentration in seawater and reduce the added amounts of a completely new magnetic powder compared to the flocculation magnetic separator 10 without the magnetic extraction unit 20 powder in figure 2.

table 2 A B C fifty 0 (do not return) thirty 40 19 25 thirty 42 eighteen twenty 65 eleven 10 87 four

In addition, if 30% of the SS components other than the magnetic powder component contained in the collected flakes are separated and removed from the collected flakes using the magnetic powder extraction unit 20, this leads to a condition in which the collected flakes initially contain an SS concentration in the seawater 30 mg / l and, therefore, this concentration of SS makes it possible to return 42% of the released collected flakes.

Accordingly, it is preferable to place the magnetic powder extraction unit 20 in the flocculation magnetic separator 10 if the SS concentration in the seawater often exceeds the maximum calculated SS concentration in the seawater or if additional quantities of collected flakes are returned in order to reduce the amounts of brand new magnetic powder that are used should also decrease.

[Additional notes]

[Explanations regarding the optimal value of the fraction of magnetic powder in magnetic flakes]

It should be noted here that targets for processing intended for treating ballast water include plankton and bacteria. In addition, if the ballast water treatment system is installed on a ship, tests must be performed to verify the performance of the processing system or instructions as determined by the regulatory authority. In accordance with the instructions, the treatment system must have sufficient performance to treat ballast water containing suspended solids (SS), such as sand, in ballast water at a maximum concentration of 50 mg / l, while meeting the discharge criteria for ballast water.

In this regard, the inventors of the present invention adopt a method of adding microparticles based on a mineral called kaolin as a model of sand or the like in a study to determine conditions for flocculation magnetic separation of plankton and bacteria.

Below, the test method will be more specifically explained in detail.

First, the aforementioned kaolin at a concentration of 50 mg / l is added to seawater containing plankton and bacteria. Then, flocculation studies in sea water are carried out by setting parameters (or variables) with the inclusion of the proportions of adding magnetic powder, inorganic flocculant and polymer flocculant. After that, the state of formation of magnetic flakes is evaluated using visual observation. Then, seawater containing magnetic flakes is introduced into the channel in which the permanent magnets are arranged in an orderly manner. Sea water is subjected to contact treatment and adsorption treatment using magnets for a given time (or several seconds). Then measure the concentration of magnetic flakes in seawater discharged from the channel, and determine the proportion of removed magnetic flakes.

The results of the evaluation study, as discussed above, clearly show that plankton and bacteria flocculate sufficiently under conditions of added proportions: polyaluminium chloride, used as an inorganic flocculant = 5 mg Al / L and polymer flocculant = 1 mg / L.

In addition, as shown in FIG. 6, the proportion of removal of magnetic flakes is likely to increase when the proportion of addition of magnetic powder increases. When the proportion of addition of magnetic powder becomes 30 mg / L or more, the proportion of removal is likely to peak. From a cost point of view, it is desirable to reduce the proportion of magnetic powder addition as much as possible. Therefore, the proportion of addition of magnetic powder is defined as 30 mg / L.

If the proportions of adding magnetic powder, inorganic flocculant and polymer flocculant are set at values such as discussed above, the content of magnetic powder with respect to magnetic flakes can be calculated using the following formula.

The content of magnetic powder in magnetic flakes (%) = (the proportion of the addition of magnetic powder) / (the proportion of the addition of kaolin + the proportion of the addition of magnetic powder + the proportion of the inorganic flocculant + the proportion of the addition of polymer flocculant) × 100 ---

(Formula 1)

Here, each value is as listed below. The proportion of adding magnetic powder = 30 mg / l; the proportion of kaolin addition = 50 mg / l; the proportion of the addition of inorganic flocculant = 5 × (78/27) = 14.4 mg / l; the proportion of the addition of polymer flocculant = 1 mg / L.

It should be noted that polyaluminium chloride, added as an inorganic flocculant, exists in the form of aluminum hydroxide (Al (OH) ₃ ) in magnetic flakes. For this reason, the proportion of addition of polyaluminium chloride is calculated by the formula: 5 mg Al / L (proportion of addition) × 78 (MW Al (OH) ₃ ) / 27 (AW Al).

If the corresponding values are substituted in formula 1, the formula will be presented as:

The content of magnetic powder in magnetic flakes (%) = 30 / (50 + 30 + 14.4 + 1) × 100 = 31.4 (%)

The authors of the present invention determine that this calculated fraction of the magnetic powder is the optimal value that allows you to provide a fraction of the removal of magnetic flakes and to minimize processing costs.

As discussed above, it should be noted that the method of recycling magnetic powder requires organizing the flow of magnetic powder for processing in order to ensure the proportion of removal of magnetic flakes and maintain the performance of their processing without lowering the content of magnetic powder to a value lower than the value calculated above.

In addition, the graph in FIG. 7 shows the proportion of return of collected flakes with respect to SS in sea water (mg / L). The return rate of collected cereal is set based on this schedule.

Description of Reference Positions

10: Flocculation magnetic separator

12: Outboard water pipe

14: Flocculation node

16: Magnetic separation unit (or magnetic separation device)

18: Return and Add Unit (or Return and Add Unit)

20: Magnetic powder extraction unit (or magnetic powder extraction device)

22: Thermal sterilization unit (or device for sterilization)

24: Monitoring node (or monitoring device)

26: High-speed agitating tank (or first agitator tank)

28: Slow agitating tank (or second agitator tank)

30: Node for supplying magnetic powder (or device for supplying magnetic powder)

32: node add flocculant

34: Pipeline

36: Site add polymer flocculant

38: Magnetic powder injection pump

40: SS concentration meter (or concentration detection device)

42: Collecting cereal return pump

44: Magnetic separation tank

46: Magnetic filter

48: conveyor

50: collecting tank for collecting cereal

52: grinding unit (or grinding device: linear chopper)

54: grinding unit (or grinding device: ultrasonic shredder)

56: Extraction unit (or extraction device)

58: Pump (or return device)

60: paddle mixer

62: Vibrator

64: Liquid

65: Ball mill (grinding unit)

66: Pure Water

68: Tank

70: Filter

72: Pipeline

74: flow meter

Claims (5)

1. Flocculation magnetic separator containing:
a first agitator tank connected to a seawater supply pipe that supplies seawater and quickly mixing seawater with added flocculant and magnetic powder that is supplied from the magnetic powder supply device to thereby form magnetic micro flakes containing magnetic powder;
a second tank with a mixer for slower mixing of the treated water, to which a polymer flocculant is added than in the first tank with a mixer, thereby increasing the size of magnetic micro flakes, for treated water containing magnetic micro flakes and discharged from the first tank with a mixer;
a magnetic separation device for collecting increased magnetic flakes, under the action of magnetic force, from the treated water, which is discharged from the second tank with a stirrer and contains increased magnetic flakes; and
a return and refill device for returning collected flakes that were collected from the magnetic separation device by scraping with a scraper to the seawater supply pipe in a position in front of the first agitator tank and in a position where flocculant is added, thereby adding collected flakes outboard water. 2. The flocculation magnetic separator according to claim 1, further comprising:
a concentration detecting device for detecting the concentration of suspended solid products in sea water, in a position before adding magnetic powder, flocculant and collected flakes; and
a control device for controlling the amount of collected flakes returned by the return and addition device and the amount of magnetic powder added by the magnetic powder supply device, based on both the concentration of suspended solids detected by the concentration detection device and the maximum concentration suspended solids in seawater set in advance. 3. The flocculation magnetic separator according to claim 2, wherein the control device stops the return process of the collected flakes supplied by the return and addition device when the concentration of suspended products detected by the concentration detection device becomes equal to the maximum concentration of suspended solid products in seawater, and at the same time, the control device controls the amount of added magnetic powder supplied by the device for supplying magnetic powder ; and
the control device increases the amount of returned collected flakes brought in by the return and addition device when the concentration of suspended solid products becomes lower than the maximum concentration of suspended solid products in sea water, and at the same time, the control device reduces the amount of added magnetic powder supplied by the magnetic powder supply device. 4. The flocculation magnetic separator according to claim 1, further comprising:
a magnetic powder extraction device that is located on the return pipe located between the return and addition device and the pipe for supplying sea water;
a magnetic powder extraction device comprising:
a chopping device for grinding collected flakes under shear;
an extraction device for selectively extracting only a component of the magnetic powder from the collected flakes, thus crushed using magnetic force; and
a return device for returning a component of the magnetic powder thus extracted into the overboard water supply pipe. 5. The flocculation magnetic separator according to claim 1, further comprising a sterilization device for sterilizing plankton and bacteria contained in the collected flakes, located in the pipeline for returning the collected flakes supplied by the return and addition device.

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