JP6810582B2 - Wastewater treatment system - Google Patents

Description

The present invention relates to a wastewater treatment system.

Exhaust gas recirculation (EGR) technology, which returns exhaust gas to the engine, is a technology for reducing the amount of nitrogen oxides (NOx) emitted from diesel engines for large ships. However, since diesel engines for large ships use heavy oil as fuel, the exhaust contains a large amount of suspended particulate matter such as carbon. Therefore, when returning the exhaust gas to the engine, it is necessary to remove suspended particulate matter from the exhaust gas (EGR gas). As a device for removing suspended particulate matter from EGR gas, there is a washing dust collector using washing water.

In order to discharge the washing water used in the washing dust collector to the outside of the ship as wastewater, it is necessary to perform wastewater treatment to separate soot and dust (solid particles such as soot) from the wastewater. The inventors of the present application have proposed as a system for performing this wastewater treatment, a wastewater treatment system including a settling tank for performing a sedimentation separation treatment and a centrifuge located downstream of the settling tank for performing a centrifugation treatment. (See Patent Document 1). The reason why the settling tank is arranged upstream of the centrifuge is to reduce the load of wastewater treatment by the centrifuge.

Japanese Unexamined Patent Publication No. 2013-255876

In the above wastewater treatment system, the rotating body provided inside the centrifuge rotates, so that the centrifuge sucks in the wastewater. Therefore, if the force of the centrifuge to take in wastewater (that is, the back pressure of the settling tank) fluctuates and temporarily increases, the soot and dust settled in the settling tank may flow out of the settling tank together with the wastewater and flow into the centrifuge. There is.

The present invention has been made in view of the above circumstances, and in a wastewater treatment system in which a centrifuge is arranged downstream of a settling tank, the force of taking in wastewater from the centrifuge fluctuates and is temporary. It is an object of the present invention to provide a wastewater treatment system capable of suppressing the outflow of soot and dust settled in the settling tank even if the size becomes large.

The wastewater treatment system according to one aspect of the present invention is a wastewater treatment system that separates soot and dust from wastewater, and performs a centrifugation treatment by taking in a settling tank for performing a sedimentation separation treatment and wastewater having undergone the sedimentation separation treatment. A centrifuge and an intermediate tank located between the settling tank and the centrifuge that temporarily stores the waste water that has undergone the settling separation process and supplies the temporarily stored waste water to the centrifuge. , Is equipped.

According to this configuration, even if the force of the centrifuge to take in wastewater fluctuates and temporarily increases, the fluctuation of the force is absorbed by the intermediate tank and is not easily transmitted to the settling tank, so that the dust settled in the settling tank Can be suppressed from flowing out of the settling tank.

In the above wastewater treatment system, a supply pipe for supplying wastewater from the settling tank to the intermediate tank is further provided, and the supply pipe has a discharge port that opens inside the intermediate tank at the downstream end, and the discharge port is It may be located at a position higher than the water surface of the wastewater stored in the intermediate tank.

According to this configuration, the wastewater discharged from the settling tank is discharged into the space in the intermediate tank and once passes through the air. Therefore, the fluctuation of the force for taking in the wastewater of the centrifuge is hardly transmitted to the settling tank, and the soot and dust settled in the settling tank can be further suppressed from flowing out from the settling tank.

In the above wastewater treatment system, the inside of the intermediate tank may be open to the atmosphere.

According to this configuration, the internal pressure of the intermediate tank is constant (that is, atmospheric pressure) regardless of the fluctuation of the force that takes in the wastewater of the centrifuge, so the fluctuation of the force that takes in the wastewater of the centrifuge is transmitted to the settling tank. There is no such thing. Therefore, it is possible to further prevent the soot and dust settled in the settling tank from flowing out from the settling tank.

In the above wastewater treatment system, the inside of the settling tank is water-sealed, and the supply pipe extends downward from a position higher than the discharge port, reaches a position lower than the discharge port, and then extends upward. It may have a trap portion leading to the discharge port.

According to this configuration, since the inside of the trap portion is always filled with wastewater, the wastewater acts as a stopper in the supply pipe, and it is possible to prevent air from flowing into the settling tank from the discharge port. As a result, it is possible to prevent a decrease in the capacity of the sedimentation separation treatment due to the inflow of air into the sedimentation tank.

In the above wastewater treatment system, when the water level of the wastewater stored in the intermediate tank reaches a predetermined upper limit position, a return pipe for returning the wastewater stored in the intermediate tank to the settling tank is further provided. May be good.

According to this configuration, the discharge port can be maintained at a position higher than the water surface of the wastewater stored in the intermediate tank.

In the above wastewater treatment system, the intermediate tank may have a return port to which the return pipe is connected, and the return port may be located at the upper limit position in the intermediate tank.

According to this configuration, when the water level of the wastewater stored in the intermediate tank reaches the upper limit position, the wastewater is discharged from the return port and returned to the settling tank via the return pipe. Therefore, it is possible to easily maintain the state in which the discharge port is located at a position higher than the water surface of the wastewater stored in the intermediate tank.

As described above, according to the above-mentioned wastewater treatment system, it is possible to prevent the soot and dust settled in the settling tank from flowing out from the settling tank.

FIG. 1 is an overall view of the wastewater treatment system according to the embodiment.

Hereinafter, the wastewater treatment system 100 according to the embodiment of the present invention will be described. FIG. 1 is an overall view of the wastewater treatment system 100. The wastewater treatment system 100 according to the present embodiment is a system for treating the wastewater discharged from the washing and dust collecting device 101, and is mounted on the hull. The cleaning dust collector 101 cleans the EGR gas returned to the engine from the exhaust gas discharged from the diesel engine for large ships.

As shown in FIG. 1, the wastewater treatment system 100 includes a settling tank 10, an intermediate tank 20, a supply pipe 30, a return pipe 40, and a centrifuge 50. Hereinafter, each of these components will be described in order.

The settling tank 10 performs a settling separation treatment for precipitating the soot and dust contained in the wastewater and separating the soot and dust from the wastewater. The settling tank 10 takes in wastewater from the washing and dust collecting device 101 via the inflow pipe 11. The inflow pipe 11 may be provided with a pump for transporting wastewater. The settling tank 10 of the present embodiment has a large number of inclined pipes having a tubular shape and an inclined axis, and when wastewater passes through the inclined pipes, dust is settled in the inclined pipes. Further, in order to prevent an adverse effect of the shaking of the hull on the settling separation process, the inside of the settling tank 10 is filled with wastewater so that air does not enter the inside of the settling tank 10. That is, the inside of the settling tank 10 is water-sealed.

The intermediate tank 20 is a tank located between the settling tank 10 and the centrifuge 50. The intermediate tank 20 temporarily stores the wastewater that has been subjected to the sedimentation separation treatment in the settling tank 10, and supplies the temporarily stored wastewater to the centrifuge 50. The intermediate tank 20 has an air inlet 21 connected to the atmosphere, and the inside of the intermediate tank 20 is open to the atmosphere. Further, the intermediate tank 20 has a return port 22 that opens to the inside at a predetermined height position on the side portion. Further, the intermediate tank 20 has a discharge port 23 at the bottom.

The supply pipe 30 is a pipe that supplies wastewater from the settling tank 10 to the intermediate tank 20. The supply pipe 30 has a discharge port 31 that opens inside the intermediate tank 20 at the downstream end. The discharge port 31 is located at a position higher than the water surface of the wastewater stored in the intermediate tank 20. Therefore, the wastewater supplied from the settling tank 10 is discharged from the discharge port 31 to the space (area filled with air) located above the intermediate tank 20.

Further, the supply pipe 30 has a J-shaped trap portion 32. When viewed from the upstream side, the trap portion 32 has a shape that extends downward from a position higher than the discharge port 31, reaches a position lower than the discharge port 31, and then extends upward to reach the discharge port 31. Since the trap portion 32 has such a shape, the inside is always filled with wastewater. As a result, the wastewater in the trap portion 32 acts as a stopper, and it is possible to prevent air from flowing into the settling tank 10 from the discharge port 31.

The return pipe 40 is a pipe for returning the wastewater stored in the intermediate tank 20 to the settling tank 10. One end of the return pipe 40 is connected to the return port 22 of the intermediate tank 20, and the other end is connected to the inflow pipe 11. In the present embodiment, when the water level of the wastewater stored in the intermediate tank 20 reaches the height at which the return port 22 is located, the wastewater is discharged from the return port 22 and settled in the settling tank 10 via the return pipe 40 and the inflow pipe 11. Returned to.

That is, in the wastewater treatment system 100 according to the present embodiment, the return port 22 is located at a predetermined upper limit position lower than the discharge port 31, and the water level of the wastewater stored in the intermediate tank 20 has reached the upper limit position. At that time, the return pipe 40 is configured to return the wastewater stored in the intermediate tank 20 to the settling tank 10. As a result, it is possible to maintain the state in which the discharge port 31 is located at a position higher than the water surface of the wastewater stored in the intermediate tank 20.

The water level of the wastewater stored in the intermediate tank 20 may be controlled by using a level meter. For example, one end of the return pipe 40 is connected to the bottom of the intermediate tank 20, and an open / close valve is provided in the return pipe 40, and the level meter detects that the water level of the wastewater stored in the intermediate tank 20 has reached the upper limit position. At that time, the on-off valve may be opened. Even in this case, the water level of the wastewater stored in the intermediate tank 20 can be maintained at an appropriate height position.

The centrifuge 50 takes in the wastewater that has been subjected to the sedimentation separation treatment in the settling tank 10, and performs a centrifugal separation treatment that separates soot and dust from the wastewater by centrifugal force. The reason why the settling tank 10 is arranged upstream of the centrifuge 50 is to reduce the load of wastewater treatment by the centrifuge 50. Further, the wastewater that has been centrifuged by the centrifuge 50 is discharged outboard via the outflow pipe 51 or returned to the cleaning dust collector 101 for reuse.

Further, the centrifuge 50 takes in wastewater from the intermediate tank 20 via the intake pipe 52 connected to the discharge port 23 of the intermediate tank 20. The intake pipe 52 is provided with an intake valve 53. Further, the centrifuge 50 is connected to the sludge tank 102 via a sludge pipe 54. In the centrifuge 50, the connection destination on the downstream side of the centrifuge 50 can be switched from the outflow pipe 51 to the sludge pipe 54, and the sludge pipe 54 can be switched to the outflow pipe 51.

Here, since the soot and dust separated by the centrifugation process gradually accumulates inside the centrifuge 50, it is necessary to perform a removal operation to remove the soot and dust on a regular basis. In the present embodiment, when performing the removal work, the intake valve 53 is closed, the connection destination on the downstream side of the centrifuge 50 is switched from the outflow pipe 51 to the sludge pipe 54, and the inside of the centrifuge 50 is air purged. Will be done. As a result, the soot and dust accumulated inside the centrifuge 50 is discharged to the sludge tank 102 through the sludge pipe 54 together with the wastewater.

On the other hand, after the removal work is completed, the connection destination on the downstream side of the centrifuge 50 is switched from the outflow pipe 51 to the sludge pipe 54, and the intake valve 53 is opened, so that the centrifuge 50 resumes the intake of wastewater. To do. During the removal operation, all the wastewater in the centrifuge 50 is once discharged, so when the centrifuge 50 resumes taking in the wastewater, the force for temporarily taking in the wastewater increases.

If the settling tank 10 and the centrifuge 50 are directly connected to each other without going through the intermediate tank 20, when the force of the centrifuge 50 to take in waste water temporarily increases, the settling tank 10 will settle. There is a risk that soot and dust will be sucked into the centrifuge 50 and flow out of the settling tank 10 and flow into the centrifuge 50. In that case, the load of wastewater treatment by the centrifuge 50 may increase sharply, and the centrifuge 50 may not function sufficiently.

On the other hand, in the wastewater treatment system 100 according to the present embodiment, since the intermediate tank 20 is arranged between the settling tank 10 and the centrifuge 50 as described above, the force of taking in the wastewater by the centrifuge 50 is strong. The intermediate tank 20 can absorb the fluctuation of the force even if it fluctuates and becomes temporarily large. As a result, it is possible to prevent the soot and dust that has settled in the settling tank 10 from flowing out and flowing into the centrifuge 50.

Further, in the present embodiment, the intermediate tank 20 has a space open to the atmosphere, and the wastewater supplied from the settling tank 10 is discharged into this space from the discharge port 31. Therefore, even if the force of the centrifuge 50 to take in wastewater fluctuates, the change of the force is not transmitted to the settling tank 10 (the back pressure of the settling tank 10 does not change), and the soot and dust settled in the settling tank 10 settle. It is possible to suppress the outflow from the tank 10 and the inflow into the centrifuge 50.

10 Sedimentation tank 20 Intermediate tank 22 Return port 30 Supply pipe 31 Discharge port 32 Trap part 40 Return pipe 50 Centrifuge 100 Wastewater treatment system

Claims (5)

A wastewater treatment system that separates soot and dust from wastewater.
A settling tank for sedimentation separation and
A centrifuge that takes in wastewater that has undergone precipitation separation treatment and centrifuges it.
An intermediate tank located between the settling tank and the centrifuge, which temporarily stores the wastewater that has undergone the settling separation treatment and supplies the temporarily stored wastewater to the centrifuge.
A supply pipe for supplying wastewater from the settling tank to the intermediate tank is provided.
The supply pipe has a discharge port that opens inside the intermediate tank at the downstream end.
A wastewater treatment system in which the discharge port is located at a position higher than the water surface of the wastewater stored in the intermediate tank . The wastewater treatment system according to claim 1 , wherein the inside of the intermediate tank is open to the atmosphere. The inside of the settling tank is water-sealed.
The supply pipe according to claim 1 or 2 , wherein the supply pipe has a trap portion extending downward from a position higher than the discharge port, reaching a position lower than the discharge port, and then extending upward to reach the discharge port. Wastewater treatment system. Any of claims 1 to 3 , further comprising a return pipe for returning the wastewater stored in the intermediate tank to the settling tank when the water level of the wastewater stored in the intermediate tank reaches a predetermined upper limit position. The wastewater treatment system described in the first section. The intermediate tank has a return port to which the return pipe is connected.
The wastewater treatment system according to claim 4 , wherein the return port is located at the upper limit position in the intermediate tank.

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