JP6378739B2 - Engine system for large ships - Google Patents

Description

The present invention relates to an engine system for large ships .

  As a technique for reducing the amount of nitrogen oxide (NOx) discharged from the engine, there is an exhaust gas recirculation (EGR) technique for returning exhaust gas to the engine. This EGR technology can also be applied to engines for large ships. However, because large marine engines use heavy oil as fuel, the exhaust contains a large amount of suspended particulate matter such as carbon. Therefore, the EGR unit of the engine system for large ships includes a scrubber that cleans exhaust gas (EGR gas) returned to the engine with a cleaning liquid.

  In the scrubber, the used cleaning liquid is discharged as scrubber waste water. This scrubber wastewater contains a large amount of dust (solid particles such as soot), and it is necessary to separate and remove the dust from the scrubber wastewater in order to discharge the scrubber wastewater to the outside of the ship. Therefore, the EGR unit of the engine system for large ships needs a waste water treatment apparatus that separates and removes dust from the scrubber waste water. The inventors of this application have proposed what provided the precipitation tank which performs a precipitation separation process as this waste water treatment apparatus (refer patent document 1).

JP2013-255876A

  By the way, it is effective to introduce a flocculant into the scrubber wastewater in order to precipitate the dust contained in the scrubber wastewater in the settling tank. Soot is likely to settle if the particle size is large, and by adding a flocculant to the scrubber wastewater, the aggregation of the dust contained in the scrubber wastewater can be promoted. However, to efficiently agglomerate the dust, it is necessary to sufficiently stir the scrubber waste water and the aggregating agent. If this agitation is performed in a sedimentation tank, the dust that has settled at the bottom of the sedimentation tank rises, and the soot that dusts up may be taken into the scrubber wastewater again.

  On the other hand, in order to prevent soot that has settled in the settling tank, the scrubber wastewater and the flocculant are agitated upstream of the settling tank to aggregate the dust, and then the scrubber wastewater containing the aggregated dust is pumped. It is conceivable to transport to a sedimentation tank. However, when the scrubber wastewater passes through the pump, the agglomerated dust can be crushed in the pump.

The present invention was made in view of such circumstances, without the precipitated dust is stirred up in the precipitation tank at the time of stirring the scrubber wastewater flocculants and dust aggregated by aggregating agent is crushed An object of the present invention is to provide an engine system for large ships equipped with a difficult wastewater treatment device.

  A wastewater treatment apparatus according to an aspect of the present invention is a wastewater treatment apparatus that separates and removes dust from scrubber wastewater generated by washing engine exhaust, and a precipitation tank that precipitates the dust contained in the scrubber wastewater; A flocculant charging unit for charging a flocculant into the scrubber waste water, a stirring unit for stirring the scrubber waste water and the flocculant, and a transport pump for pumping the scrubber waste water to the settling tank. Stirs the scrubber wastewater and the flocculant in a pressure-feed passage located between the transport pump and the settling tank.

  According to this configuration, since the scrubber waste water and the flocculant are stirred in the pumping flow channel upstream of the settling tank, the dust that has settled in the settling tank does not rise by the stirring. In addition, since the agitation unit agitates the scrubber wastewater and the flocculant in the pumping flow channel located between the conveyance pump and the settling tank, the agglomerated dust particles by agitation of the scrubber wastewater and the flocculant pass through the conveyance pump. There is nothing. Therefore, the agglomerated dust can be conveyed to the settling tank without being crushed, and the agglomerated dust can be precipitated in the settling tank.

  Further, in the waste water treatment apparatus, the stirring unit is disposed in a stationary state in the pumping flow path, and has a diverting member that changes a flow direction of the scrubber waste water flowing in the pumping flow path. May be.

  According to this configuration, the direction of the scrubber wastewater flow can be changed by the deflecting member stationary in the pumping flow path, whereby the scrubber wastewater and the flocculant can be agitated. Therefore, power for stirring the scrubber waste water and the flocculant becomes unnecessary, and the structure of the stirring unit can be simplified. As a result, the wastewater treatment apparatus can be reduced in size.

As described above, according to the above-described wastewater treatment apparatus, the dust settled in the settling tank does not rise when stirring the scrubber wastewater and the flocculant, and the dust aggregated by the flocculant is difficult to be crushed.

FIG. 1 is an overall view of an engine system including a wastewater treatment apparatus. FIG. 2 is an overall view of the wastewater treatment apparatus. FIG. 3 is an overall view of a wastewater treatment apparatus according to another embodiment.

(First embodiment)
Hereinafter, the wastewater treatment apparatus 100 according to the first embodiment of the present invention will be described.

<Engine system>
First, the engine system 101 provided with the waste water treatment apparatus 100 will be described. FIG. 1 is an overall view of the engine system 101. In FIG. 1, the thick dashed line indicates the flow of exhaust gas and EGR gas (exhaust gas returning to the engine), and the thick solid line indicates the flow of fresh air and scavenging gas (fresh air plus EGR gas). ing.

  The engine system 101 is an engine system for a large ship and is an engine 102 that is a two-stroke diesel engine, a scavenging flow passage 103 that supplies scavenging to the engine 102, and an exhaust that discharges exhaust discharged from the engine 102 to the outside. A flow path 104, a supercharger 105 that is driven by the energy of exhaust gas to boost the fresh air, an EGR unit 106 that extracts exhaust gas from the exhaust flow path 104 and supplies it to the scavenging flow path 103, and a scrubber wastewater described later And a wastewater treatment apparatus 100 for performing

  The EGR unit 106 includes an EGR passage 10 that connects the scavenging passage 103 and the exhaust passage 104, a scrubber 20 that is provided in the EGR passage 10 and that cleans the EGR gas and discharges the used cleaning liquid as scrubber waste water. And an EGR blower 30 that is provided in the passage 10 and boosts the exhaust gas and adjusts the flow rate of the EGR gas. The wastewater treatment apparatus 100 separates and removes dust from the scrubber wastewater discharged from the scrubber 20 described above, that is, the scrubber wastewater generated by washing the exhaust of the engine 102.

<Waste water treatment equipment>
Subsequently, the wastewater treatment apparatus 100 will be described in more detail. FIG. 2 is an overall view of the wastewater treatment apparatus 100. The wastewater treatment apparatus 100 separates and removes dust from the scrubber wastewater, and then discharges the scrubber wastewater to the outside of the ship or returns it to the scrubber 20 for reuse. As shown in FIGS. 1 and 2, the wastewater treatment apparatus 100 includes a sedimentation tank 41, a centrifuge 42, a flocculant charging unit 43, a stirring unit 44, and a transport pump 45.

  The sedimentation tank 41 performs a precipitation separation process that precipitates the dust contained in the scrubber wastewater and separates and removes the dust from the scrubber wastewater. The sedimentation tank 41 of the present embodiment has a large number of cylindrical inclined tubes whose axis is inclined, and dust is deposited on the inclined tubes when waste water passes through the inclined tubes. The precipitated dust is collected at the bottom of the precipitation tank 41.

  The centrifuge 42 takes in the scrubber wastewater that has been subjected to the precipitation separation process in the settling tank 41, and performs a centrifugal separation process that separates and removes dust from the scrubber wastewater by centrifugal force. The sedimentation tank 41 is disposed upstream of the centrifuge 42 because the soot and dust having a relatively large particle size is separated and removed by the sedimentation tank 41 so as to be disposed downstream of the sedimentation tank 41. This is to reduce the burden of wastewater treatment of the separator 42. The scrubber waste water that has been subjected to the centrifugal separation process by the centrifuge 42 is discharged out of the ship or returned to the scrubber 20 for reuse.

  Here, the wastewater treatment apparatus 100 according to the present embodiment is formed with a pressure feed passage 46 that is located between the transport pump 45 and the sedimentation tank 41 and through which the scrubber wastewater flows toward the sedimentation tank 41. Specifically, as shown in FIG. 2, tubular members 47 and 49 and a box-like member 48 connected to each other are provided between the transport pump 45 and the sedimentation tank 41, and the pressure feed flow is provided inside these members. A path 46 is formed. Moreover, the pumping flow path 46 is filled with scrubber waste water.

  The flocculant throwing unit 43 throws the flocculant into the scrubber wastewater flowing through the pumping flow path 46. By adding a flocculant to the scrubber wastewater, the aggregation of the dust contained in the scrubber wastewater is promoted. The kind of flocculant is not specifically limited, A well-known flocculant can be used. In the present embodiment, the flocculant feeding unit 43 feeds the flocculant upstream from the stirring unit 44, but the flocculant may be fed near the stirring unit 44. Further, in order to stir the scrubber waste water and the flocculant with the transport pump 45, the flocculant input unit 43 may input the flocculant upstream of the transport pump 45.

  The stirring unit 44 is a part for stirring the scrubber waste water and the flocculant. In the present embodiment, the scrubber waste water and the flocculant are agitated in the pressure-feed passage 46 corresponding to the inside of the box-shaped member 48. The stirring unit 44 includes a stirring plate 50 located inside the box-shaped member 48 and a rotation motor 51 that rotates the stirring plate 50. As the stirring plate 50 rotates, the scrubber waste water and the flocculant are stirred.

  The transport pump 45 is a pump that pumps scrubber wastewater to the sedimentation tank 41. The transport pump 45 pressurizes the scrubber waste water upstream of the stirring unit 44. The pressure applied to the scrubber wastewater from the transfer pump 45 is converted into kinetic energy, and the scrubber wastewater flows to the settling tank 41. In the present embodiment, since the scrubber wastewater continuously flows in the pressure feed passage 46, the scrubber wastewater can be transported to the sedimentation tank 41 only by the transport pump 45.

  The above is the configuration of the wastewater treatment apparatus 100 according to the present embodiment. As described above, in the wastewater treatment apparatus 100 according to the present embodiment, the agitation of the dust contained in the scrubber wastewater is promoted by agitating the scrubber wastewater and the flocculant in the agitation unit 44, and the sedimentation treatment is efficiently performed in the precipitation tank 41. It can be performed.

  Furthermore, in this embodiment, since the scrubber waste water and the flocculant are agitated in the pumping flow path 46, the dust that has settled in the sedimentation tank 41 does not rise by this agitation. In the present embodiment, since the agitation unit 44 agitates the scrubber waste water and the flocculant in the pressure-feed channel 46, the dust aggregated by the flocculant does not pass through the conveyance pump 45 and is crushed by the conveyance pump 45. It never happens.

(Second Embodiment)
Next, the wastewater treatment apparatus 200 according to the second embodiment will be described. The wastewater treatment apparatus 200 according to the present embodiment is different from the wastewater treatment apparatus 100 according to the first embodiment in the configuration of the pumping flow path 46 and the stirring unit 44, but the wastewater treatment apparatus 100 according to the first embodiment is otherwise. And basically the same.

  FIG. 3 is an overall view of the wastewater treatment apparatus 200 according to the present embodiment. In the present embodiment, the scrubber wastewater is pumped to the sedimentation tank 41 by the transport pump 45 as in the case of the first embodiment. However, as shown in FIG. 3, in the present embodiment, a pressure-feed passage 46 is formed inside the tubular members 47, 49, 52.

  The stirrer 44 according to the present embodiment is a so-called static mixer that is disposed in a stationary state in the pressure-feeding channel 46 and changes the direction of the scrubber waste water flowing in the pressure-feeding channel 46. 53. The diverting member 53 has a plurality of diverting plates 54 having different shapes connected along the axial direction of the tubular member 52. The scrubber wastewater flowing in the pressure-feed channel 46 collides with the direction change plates 54, so that the flow direction is changed in a complicated manner, and the scrubber wastewater and the flocculant are agitated.

  Since the wastewater treatment apparatus 200 according to the present embodiment is configured as described above, power for stirring the scrubber wastewater and the flocculant becomes unnecessary, and the structure of the stirring unit 44 can be simplified. . As a result, the wastewater treatment apparatus 200 can be reduced in size.

  In the above, the case where the wastewater treatment apparatuses 100 and 200 treat the scrubber wastewater discharged from the scrubber 20 of the EGR unit 106 has been described. However, the wastewater treatment apparatuses 100 and 200 are from the SOx scrubber that treats the entire exhaust gas. The scrubber waste water discharged may be treated. The SOx scrubber mainly separates and removes SOx from the exhaust gas, but the scrubber wastewater discharged from the SOx scrubber also contains soot and dust.

41 Precipitation tank 43 Coagulant charging unit 44 Stirring unit 45 Conveying pump 46 Pumping flow path 53 Turning member 100 Wastewater treatment device 102 Engine 200 Wastewater treatment device

Claims (4)

An engine that is a two-stroke diesel engine;
An engine system for a large marine vessel and a waste water treatment apparatus for separating and removing dust from the scrubber waste water resulting from washing the exhaust of the engine,
The wastewater treatment device is
A settling tank for precipitating the dust contained in the scrubber waste water;
A flocculant charging unit for charging the flocculant into the scrubber waste water;
A stirring section for stirring the scrubber wastewater and the flocculant;
A transport pump for pumping the scrubber wastewater to the settling tank,
The engine system in which the agitation unit agitates the scrubber wastewater and the flocculant in a pressure-feed passage located between the transport pump and the settling tank. 2. The engine system according to claim 1, wherein the agitation unit is disposed in a stationary state in the pumping flow path and includes a diverting member that changes a flow direction of the scrubber wastewater flowing in the pumping flow path. The engine system according to claim 2, wherein the diverting member has a plurality of diverting plates having different shapes. The engine system according to any one of claims 1 to 3, wherein the flocculant charging unit charges the flocculant upstream of the transport pump.

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