JP5970357B2 - Dehydration processing apparatus, dehydration processing program and method thereof - Google Patents

Description

  The present invention relates to a dehydration processing apparatus, a dehydration processing program, and a method thereof. More specifically, the present invention relates to a dehydration processing apparatus, a dehydration processing program, and a method thereof for dehydrating a clay slurry to generate a dehydrated cake.

  There are known dredging works carried out to secure water depth, prevent the generation of odors and protect aquatic organisms by removing sediments, garbage and sludge accumulated in harbors, lakes, rivers, ponds and digging ing. Dredged mud generated during dredging work is a liquid with a high water content and is also called dredged sludge.

  A high pressure filter press type dehydrator is used as a method for separating and reducing moisture from a stock solution (also referred to as a slurry) obtained by removing dust, stones and gravel from sludge. In the dehydration process by the high-pressure filter press dehydrator, first, a low-pressure pump with a relatively large discharge amount is started, and the slurry is transferred from the slurry tank in which the slurry is stored to the filter chamber of the high-pressure filter press dehydrator. Fill the chamber rapidly. Next, a high-pressure pump having a relatively high high-pressure discharge pressure is started to drive the slurry into the filter chamber at a high pressure. Before starting the high-pressure pump, the low-pressure driving by the low-pressure pump having a relatively large discharge amount is performed for a certain time, thereby shortening the filtration time and improving the filtration efficiency.

JP 08-257317 A

  However, the density of the slurry stored in the slurry tank changes over time due to differences in drowning sea areas. For this reason, when the low pressure implantation time, which is the time for performing low pressure implantation, is fixed to a certain time, the slurry density in the filter chamber after low pressure implantation changes according to the density of the slurry stored in the slurry tank. If high-pressure driving is performed in a state where the slurry density in the filter chamber is low, water hammer may be generated in the filter chamber and the high-pressure filter press-type dehydrator may be damaged. On the other hand, when the slurry density in the filter chamber rises to a certain extent, the slurry cannot be pressed into the filter chamber by the low pressure pump, and the slurry cannot be supplied into the filter chamber and cannot be filtered. In this state, extra driving that does not contribute to filtration is performed, and time and power may be wasted.

  Accordingly, an object of the present invention is to provide a dehydration processing apparatus, a dehydration processing program, and a method thereof capable of controlling a low pressure driving time so that the dehydration time is shortened in a dehydration processing apparatus having a high pressure filter press type dehydrating apparatus. To do.

  In order to achieve the above object, a dehydration apparatus according to the present invention includes a slurry tank that stores slurry contained in sludge, a density meter that detects the density of the slurry stored in the slurry tank, and a filter that can be opened and closed. A high-pressure filter press-type dehydrator that has a chamber and dehydrates the slurry in the filter chamber to produce a dehydrated cake, a low-pressure pump that transfers the slurry stored in the slurry tank to the filter chamber, and a slurry stored in the slurry tank In order to pressurize the filter with a discharge pressure higher than the discharge pressure of the low-pressure pump and press-fit it into the filter chamber, a high-pressure pump that is started after a low-pressure driving time has elapsed since the start of the low-pressure pump, a low-pressure pump, And a control unit that compares the detected slurry density with the threshold density and determines the low pressure implantation time based on the comparison.

  Furthermore, in the dehydration processing apparatus according to the present invention, when the slurry density is smaller than the threshold density, the control unit determines the low pressure implantation time as the first implantation time, and the slurry density is larger than the threshold density. In some cases, it is preferable to determine the low pressure implantation time at the second implantation time which is shorter than the first implantation time.

  Furthermore, in the dehydration processing apparatus according to the present invention, the threshold density is equal to the dehydration time when the low pressure implantation time is the first implantation time and the dehydration time when the low pressure implantation time is the second implantation time. It is preferable that the density becomes.

  Furthermore, in the dehydration processing apparatus according to the present invention, the slurry density is preferably a density detected before the low-pressure pump is started.

  Furthermore, the dehydration method according to the present invention detects the density of the slurry contained in the sludge stored in the slurry tank, compares the detected slurry density with the threshold density, and based on the comparison result, After starting the low-pressure pump that transfers the slurry stored in the slurry tank to the filter chamber of the high-pressure filter press type dehydrator, pressurize the slurry stored in the slurry tank at a discharge pressure higher than the discharge pressure of the low-pressure pump. Determining the low pressure driving time, which is the time until the high pressure pump press-fitted into the filter chamber is started, starting the low pressure pump, and starting the high pressure pump after the low pressure driving time has elapsed since the low pressure pump was started It is characterized by that.

  Furthermore, the dehydration processing program according to the present invention detects the density of the slurry contained in the sludge stored in the slurry tank, compares the detected slurry density with the threshold density, and based on the comparison result, After starting the low-pressure pump that transfers the slurry stored in the slurry tank to the filter chamber of the high-pressure filter press type dehydrator, pressurize the slurry stored in the slurry tank at a discharge pressure higher than the discharge pressure of the low-pressure pump. Determines the low pressure driving time, which is the time until the high pressure pump that press-fits the filter chamber starts, starts the low pressure pump, and starts the high pressure pump after the low pressure driving time has elapsed since the low pressure pump started. It is made to perform.

  In the dehydration processing apparatus, the dehydration processing program, and the method thereof according to the present invention, the low pressure implantation time is determined by the detected slurry density, and therefore the dehydration processing apparatus capable of controlling the low pressure implantation time so as to shorten the dehydration time, dehydration It has become possible to provide a processing program and a method thereof.

It is a figure which shows an example of a dehydration processing system. It is a figure which shows an example of a dehydration processing apparatus. It is a conceptual diagram of a high pressure pump. It is a figure which shows the spin-drying | dehydration process of a high pressure filter press type dehydrator. It is a figure which shows the functional block of a control part. It is a figure which shows the relationship between the slurry density and dehydration time in a dehydration processing apparatus. It is a figure which shows an example of the dehydration processing flow of a dehydration processing apparatus. (A) is a figure which shows an example of the fluctuation | variation of the slurry density of a slurry tank, (b) is a figure which shows an example of a time-dependent change of the consumption current of a dehydration processing apparatus, (c) is the slurry density of a slurry tank, and It is a figure which shows an example of the relationship with the power consumption of a dehydration processing apparatus.

  Hereinafter, a dehydrating apparatus according to the present invention will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, and extends to equivalents to the invention described in the claims.

  FIG. 1 is a diagram illustrating an example of a dehydration processing system.

  The dehydration processing system 100 includes a transport / pumping unit 110, a pretreatment unit 120, a mud storage unit 130, a reaction unit 140, a high-pressure dehydration processing unit 150, and a water treatment unit 160.

  The transport / pumping unit 110 includes a clay ship 111, a clam shell 112, and a receiving device 113. The clay ship 111 carries dredged soil from the dredging point to the dehydration processing system 100. The clam shell 112 transfers the dredged material carried by the earth ship 111 to the receiving device 113. The receiving device 113 has a vibrating screen, and after removing foreign matters such as driftwood contained in the clay transferred by the clamshell 112, pretreats the clay via a belt conveyor. To the unit 120.

  The pre-processing unit 120 includes a receiving trommel 121, a gravel removal device 122, a trommel belt conveyor 123, and a gravel belt conveyor. The receiving trommel 121 has a cylindrical rotating portion, and rotates the rotating portion to remove impurities such as shells and stones that have not been removed by the clamshell 112 and stones. The gravel removing device 122 removes gravel from the dredged material by guiding the dredged material from which impurities and stones have been removed by the receiving trommel 121 onto a screen having a horizontal plane that vibrates in the vertical direction. The trommel belt conveyor 123 conveys the foreign substances and stones removed by the receiving trommel 121 to a foreign substance collection place. The gravel conveyor belt 124 conveys the gravel removed by the gravel removal device 122 to a gravel collection station.

  The mud storage unit 130 includes a plurality of concentration adjustment tanks 131 and a plurality of mud storage tanks 132. Each of the plurality of concentration adjusting tanks 131 generates muddy water by mixing dilution water supplied via a dilution water tank (not shown) and the clay from which the gravel has been removed by the gravel removing device 122. Each of the plurality of mud storage tanks 132 stores the muddy water generated in the plurality of concentration adjustment tanks 131. Each of the plurality of concentration adjusting tanks 131 and the plurality of mud storage tanks 132 has a stirrer. The stirrer rotates at a constant speed and prevents muddy water from settling.

  The reaction unit 140 includes a plurality of reaction tanks 141, a PAC tank 142, a slaked lime storage tank 143, a plurality of slurry tanks 10, and a low pressure pump 15. In the plurality of reaction tanks 141, muddy water is transferred from the plurality of mud storage tanks 132 through pipes connected to the plurality of mud storage tanks 132, respectively. PAC (Poly Aluminum Chioride, polyaluminum chloride) is injected into the pipe connecting the plurality of mud storage tanks 132 and the plurality of reaction tanks 141 from the PAC tank. Further, slaked lime is injected from the slaked lime storage tank 143 into each of the plurality of reaction tanks 141. PAC and slaked lime are dehydration aids, and the PAC is agitation with the mud water by the stirring device inside the reaction tank 141, thereby agglomerating and agglomerating fine particles present in the mud water. In addition, slaked lime contributes to an increase in the strength of the dehydrated cake. The low-pressure pump 15 is a pump having a large discharge amount but a small head, that is, a low discharge pressure, and is disposed in each of the slurry tanks 10.

  The high-pressure dehydration processing unit 150 includes a high-pressure pump 20, a high-pressure filter press-type dewatering device 30, a drainage tank 40, a dewatered cake first belt conveyor 41, and a dewatered cake second belt conveyor 42. The high-pressure pump 20 is a pump whose discharge amount is smaller than that of the low-pressure pump 15 but whose head is larger than that of the low-pressure pump 15, that is, whose discharge pressure is higher than that of the low-pressure pump 15. When the high-pressure pump 20 is stopped, the slurry transferred from the low-pressure pump 15 is transferred to the filter chamber of the high-pressure filter press-type dehydrator 30 without being pressurized. Further, when the high pressure pump 20 is in operation, the high pressure pump 20 pressurizes the slurry transferred from the low pressure pump 15 and press-fits it into the filter chamber of the high pressure filter press type dehydrator 30. The high-pressure filter press-type dehydrator 30 has a plurality of filter chambers, and dehydrates the slurry transferred by the low-pressure pump 15 and the high-pressure pump 20 to generate a dehydrated cake. The drainage tank 40 is a tank that receives drainage generated during dehydration in the filtration chamber of the high-pressure filter press-type dehydrator 30. The first belt conveyor 41 for dehydrated cake and the second belt conveyor 42 for dehydrated cake convey the dehydrated cake generated by the high-pressure filter press-type dewatering device 30.

  The water treatment unit 160 includes a purification device 161, a discharge water tank 162, a purification agent injection device 163, and a neutralization device 164. The purification device 161 purifies the filtrate by mixing the filtrate transferred from the drainage tank 40, the PAC injected from the PAC tank, and the purification agent injected from the purification agent injection apparatus. The discharge water tank 162 discharges the filtrate purified by the purification device after adjusting the pH with a neutralizing agent injected from the neutralization device.

  FIG. 2 is a diagram illustrating the dehydration processing apparatus 1 included in the dehydration processing system 100. In FIG. 2, pipes 201 to 204 through which slurry flows are indicated by solid lines, pressure oil pipes 501 to 504 through which pressure oil flows are indicated by alternate long and short dash lines, and signal lines 601 to 608 used for transmission of electric signals are indicated by broken lines. It is.

  The dehydration apparatus 1 includes a slurry tank 10, a low pressure pump 15, a high pressure pump 20, a high pressure filter press type dehydrator 30, a drain tank 40, a first belt conveyor 41 for dehydrated cake, and a second dehydrated cake second. Belt conveyor 42. The dehydration apparatus 1 further includes a pressure oil device 50 and a control unit 60.

  The slurry tank 10 includes a stirring device 11, a water level detector 12, an inflow valve 13, and a density meter 14.

  The stirring device 11 includes a propeller-shaped stirrer and a motor that drives the stirrer. The slurry in the slurry tank 10 is agitated by rotating the stirrer of the agitator 11. When the slurry inside the slurry tank 10 is stirred, the density of the slurry becomes uniform inside the slurry tank 10.

  The water level detector 12 has a reference electrode that is the longest electrode, a low water level detection electrode that is the second longest electrode, and a high water level detection electrode that is the shortest electrode. The water level detector 12 transmits a low water level signal to the control unit 60 via the signal line 603 when the reference electrode and the low water level detection electrode are disconnected. In addition, the water level detector 12 transmits a high water level signal to the control unit 60 via the signal line 603 when the reference electrode and the high water level detection electrode are conducted.

  The inflow valve 13 is an electric valve controlled by the control unit 60 and is disposed between the pipes 201 and 202. The control unit 60 transmits an open signal to the inflow valve 13 when receiving a low water level signal from the water level detector 12, and sends a close signal to the inflow valve 13 when receiving a high water level signal from the water level detector 12. Send. The inflow valve 13 opens when receiving an open signal, and the inflow of slurry from the reaction tank 141 to the slurry tank 10 starts. The inflow valve 13 is closed when receiving a close signal, and the inflow of the slurry from the reaction tank 141 to the slurry tank 10 is stopped.

  The density meter 14 is a gamma ray density meter, detects the slurry density inside the slurry tank 10, and transmits a slurry density signal corresponding to the detected slurry density to the control unit 60 via the signal line 601.

  The low-pressure pump 15 is a spiral pump driven by a three-phase motor. Compared with the high-pressure pump 20, the low-pressure pump 15 has a higher discharge amount but a lower discharge pressure. When the low pressure pump 15 receives the activation command signal from the control unit 60 via the signal line 604, the low pressure pump 15 is activated and transmits an activation confirmation signal to the control unit 60. Further, when the low pressure pump 15 receives a stop command signal from the control unit 60 via the signal line 604, the low pressure pump 15 stops and transmits a stop confirmation signal to the control unit 60.

  FIG. 3 is a conceptual diagram of the high-pressure pump 20. In FIG. 3, the pipe through which the slurry flows is indicated by a solid line, and the pressure oil pipe through which the pressure oil or hydraulic oil flows is indicated by a dashed line.

  The high-pressure pump 20 includes a first pump chamber 21, a second pump chamber 22, a first suction valve 23, a first discharge valve 24, a second suction valve 25, a second discharge valve 26, and a metering cylinder 27. And a drive cylinder 28.

  The first pump chamber 21 has a first hydraulic oil chamber 21p, a first intermediate chamber 21m, and a first suction chamber 21w. In the first hydraulic oil chamber 21p, hydraulic oil flows in and out in accordance with the movement of the metering cylinder 27. The first intermediate chamber 21m contains a liquid mixed with antifreeze and is adjacent to the first hydraulic oil chamber 21p and the first suction chamber 21w via a rubber film. The rubber films located at both ends of the first intermediate chamber 21m repeat the uneven motion according to the flow of hydraulic oil flowing into and out of the first hydraulic fluid chamber 21p. The first suction / discharge chamber 21w sucks and discharges slurry according to the movement of the rubber film positioned between the first intermediate chamber 21m.

  The second pump chamber 22 includes a second hydraulic oil chamber 22p, a second intermediate chamber 22m, and a second suction / discharge chamber 22w. In the second hydraulic oil chamber 22p, hydraulic oil flows in and out in accordance with the movement of the metering cylinder 27. The second intermediate chamber 22m includes a liquid mixed with an antifreeze liquid, and is adjacent to the second hydraulic oil chamber 22p and the second suction / discharge chamber 22w via a rubber film. The rubber films positioned at both ends of the second intermediate chamber 22m repeat the uneven motion according to the flow of hydraulic oil flowing into and out of the second hydraulic oil chamber 22p. The second suction / discharge chamber 22w sucks and discharges slurry according to the movement of the rubber film positioned between the second intermediate chamber 22m.

  The first intake valve 23 is controlled to be opened and closed by a double-acting pressure oil cylinder during operation, and is opened when slurry is sucked into the first suction chamber 21w of the first pump chamber 21, The slurry is closed when the slurry is discharged from the first suction / discharge chamber 21w of the first pump chamber 21.

  When the first discharge valve 24 is in operation, the first discharge valve 24 is controlled to be opened and closed by a double-acting pressure oil cylinder, and is closed when slurry is sucked into the first suction chamber 21w of the first pump chamber 21, The slurry is opened when the slurry is discharged from the first suction / discharge chamber 21w of the first pump chamber 21.

  When the second intake valve 25 is in operation, the second intake valve 25 is controlled to be opened and closed by a double-acting pressure oil cylinder, and is opened when slurry is sucked into the second suction chamber 22w of the second pump chamber 22, The slurry is closed when the slurry is discharged from the second suction / discharge chamber 22w of the second pump chamber 22.

  When the second discharge valve 26 is in operation, the second discharge valve 26 is controlled to be opened and closed by a double-acting pressure oil cylinder, and is closed when slurry is sucked into the second suction chamber 22w of the second pump chamber 22, The slurry is opened when the slurry is discharged from the second suction / discharge chamber 22w of the second pump chamber 22.

  The metering cylinder 27 has a drive shaft coupled to the drive cylinder 28 and a partition wall coupled to the drive shaft, and according to the movement of the drive shaft, the first hydraulic oil chamber 21p of the first pump chamber 21 and The hydraulic oil is alternately introduced into and out of the second hydraulic oil chambers 22p of the second pump chamber 22.

  The drive cylinder 28 has a drive shaft coupled to the metering cylinder 27 and a partition wall coupled to the drive shaft. The drive cylinder 28 moves the drive shaft in the left-right direction according to the pressure oil supplied from the pressure oil device 50 via the pressure oil pipes 501 and 502.

  When the high pressure pump 20 is stopped, the first suction valve 23, the first discharge valve 24, the second suction valve 25, and the second discharge valve 26 are all opened, and the slurry transferred from the low pressure pump 15 is discharged. The sample is transferred to the high-pressure filter press-type dehydrator 30 without being pressurized.

  When operating, the high-pressure pump 20 pressurizes and transfers the slurry with hydraulic oil inside the first pump chamber 21 and the second pump chamber 22. Since the pressure is applied inside the first pump chamber 21 and the second pump chamber 22, the slurry can be transferred at a high discharge pressure by operating the high-pressure pump 20. However, since the discharge amount of the high-pressure pump 20 depends on the capacities of the first suction chamber 21w and the second suction chamber 22w, it is smaller than the discharge amount of the low-pressure pump 15. When the high-pressure pump 20 is in operation, the slurry that is discharged from the low-pressure pump 15 but is not sucked into the high-pressure pump 20 returns to the slurry tank 10 via the return valve 205.

  The high pressure filter press dehydrator 30 includes a plurality of filter frames 31, a pressure gauge 35, and a filter frame drive unit 36. Each of the plurality of filter frames 31 forms a plurality of filter chambers between adjacent filter frames 31. The pressure gauge 35 is a diaphragm pressure gauge, detects the pressure in the filtration chamber, and transmits a filtration chamber pressure signal corresponding to the detected filtration chamber pressure to the control unit 60 via the signal line 605. The filter frame drive unit 36 is controlled to move the plurality of filter frames 31 in the axial direction orthogonal to the filter frame 31 by the pressure oil supplied from the pressure oil device 50 via the pressure oil pipes 503 and 504. When pressure oil is press-fitted into the filter frame drive unit 36, the plurality of filter frames 31 are arranged in close contact with each other, and a plurality of filter chambers are formed between adjacent filter frames 31. When the pressure oil is discharged from the filter frame driving unit 36, the plurality of filter frames 31 are arranged at predetermined intervals.

  FIG. 4 is a view showing a dehydration process of the high pressure filter press type dehydrator 30. 4A shows the preparation process, FIG. 4B shows the filtration process, FIG. 4C shows the residual liquid treatment process, and FIG. 4D shows the frame opening process.

  First, in the preparatory process shown in FIG. 4A, the high pressure filter press-type dehydrator 30 is configured such that pressure oil is press-fitted into the filter frame drive unit 36, and a plurality of filter frames 31 are arranged close to each other. A chamber is formed. A filter cloth 32 woven with nylon is disposed on each side surface of the plurality of filter frames 31. Since the filter cloths 32 are respectively arranged on the side surfaces of the plurality of filter frames 31, the filter chamber formed by arranging the filter frames 31 close to each other has a configuration in which the filter cloth is sandwiched between the end surfaces.

  Next, in the filtration step shown in FIG. 4B, in the high pressure filter press-type dehydrator 30, the slurry 301 is pressed into the filter chamber from the low pressure pump 15 and the high pressure pump 20. The water content of the slurry press-fitted into the filter chamber is discharged as filtered water 302 to the outside of the filter frame 31 from the filter channel formed inside the filter frame 31 through the filter cloth 32. A dewatered cake 303 is gradually formed from the dewatered slurry inside the filter frame. The filtered water 302 discharged to the outside of the filter frame 31 is stored in the filtered water tank 40. The filtrate 302 stored in the filtrate tank 40 is transferred to the purification device 161 of the water treatment unit 160 by a pump (not shown). The filtration process is continued until the pressure inside the filtration chamber of the high-pressure filter press-type dehydrator 30 reaches 4 [MPa]. Since the dehydration apparatus 1 presses the slurry into the filter chamber of the high-pressure filter press-type dehydrator 30 with the high-pressure pump 20 having a high discharge pressure, the pressure inside the filter chamber of the high-pressure filter press-type dehydrator 30 is 4 The pressure can be increased to [MPa]. By filtering at a high pressure, it is possible to significantly reduce the volume of the clay by generating a dehydrated cake 301 having a water content ratio close to the plastic limit.

  Next, in the residual liquid treatment step shown in FIG. 4 (c), the high pressure filter press-type dehydrator 30 is configured such that after the low pressure pump 15 and the high pressure pump 20 are stopped, the residual liquid of the injected slurry 301 is supplied to the filter frame. It is discharged from the part by air blow. When the residual liquid of the slurry 301 is discharged from the filter frame, the dehydrated cake 303, which is a solid substance, remains inside the filter frame while being sandwiched between the inner side surfaces of the filter chamber.

  In the frame opening process shown in FIG. 4D, the high pressure filter press-type dehydrator 30 discharges the pressure oil from the filter frame drive unit 36, and the plurality of filter frames 31 are arranged at predetermined intervals. The When the plurality of filter frames 31 are arranged at a predetermined interval from each other, the dehydrated cake 303 sandwiched between the pair of filter frames 31 falls downward. The dewatered cake 303 that has fallen is transported to the dewatered cake stacking site by the first belt conveyor 41 for dehydrated cake and the second belt conveyor 42 for dehydrated cake located below the high pressure filter press type dewatering device 30.

  The drainage tank 40 is a water tank that stores drainage discharged from the high-pressure filter press-type dehydrator 30, and transfers the filtrate stored by a pump (not shown) to the purification device 161 of the water treatment unit 160.

  The first belt conveyor 41 for dewatered cake is a belt conveyor driven by a motor 43 and is located below the high-pressure filter press-type dewatering device 30 and carries the dehydrated cake dropped from the high-pressure filter press-type dewatering device 30. The motor 43 is controlled by the control unit 60. The motor 43 starts when it receives a start command signal from the control unit 60 via the signal line 607 and stops when it receives a stop command signal from the control unit 60.

  The dewatered cake second belt conveyor 42 is a belt conveyor driven by a motor 44, located below one end of the dehydrated cake first belt conveyor 41, and dehydrated conveyed by the dehydrated cake second belt conveyor 42. Transport cake to dewatering cake dump. The motor 44 is controlled by the control unit 60. The motor 44 starts when it receives a start command signal from the control unit 60 via the signal line 608, and stops when it receives a stop command signal from the control unit 60.

  The pressure oil device 50 includes a pressure oil tank that stores hydraulic oil, a pressure oil pump that applies a predetermined pressure to the hydraulic oil inside the pressure oil tank and discharges it as pressure oil, and a pressure oil discharged from the pressure oil pump. And a direction switching valve that selects whether the pressure oil pipes 501 to 504 are sent out. The direction switching valve of the pressure oil device 50 is controlled by the control unit 60. When the direction switching valve of the pressure oil device 50 receives the first high-pressure pump discharge signal from the control unit 60 via the signal line 606, the pressure oil is sent to the high-pressure pump 20 via the pressure oil pipe 501. On the other hand, when the second high pressure pump discharge signal is received from the control unit 60 via the signal line 606, the direction switching valve of the pressure oil device 50 sends pressure oil to the high pressure pump 20 via the pressure oil pipe 502. The feeding from the direction switching valve of the pressure oil device 50 to the pressure oil pipes 501 and 502 is executed alternately at predetermined time intervals. When the direction switching valve of the pressure oil device 50 receives the filter chamber formation signal from the control unit 60 via the signal line 606, it sends the pressure oil to the filter frame drive unit 36 via the pressure oil pipes 503 and 504. In addition, when the direction switching valve of the pressure oil device 50 receives the filter chamber opening signal from the control unit 60 via the signal line 606, the sending of the pressure oil to the filter frame drive unit 36 is finished.

  The control unit 60 is a computer that includes a calculation unit 61, a storage unit 62, and an I / O unit 63. The calculation unit 61 implements each function such as control of the dehydration apparatus 1 by executing a predetermined computer program stored in the storage unit 62. The control unit 60 can be formed using, for example, a computer such as a server or a state machine also called a personal computer or a sequencer.

  FIG. 5 is a diagram illustrating functional blocks of the control unit 60.

  The control unit 60 includes a dehydration processing device control unit 611, a slurry density storage unit 612, a low pressure implantation time determination unit 613, a low pressure pump control unit 614, a high pressure pump control unit 615, and a filtration chamber pressure determination unit 616. Have.

  When detecting that a dehydration start button (not shown) is pressed, the dehydration processing device controller 611 transmits a filter chamber formation signal to the direction switching valve of the pressure oil device 50 via the signal line 606. When the filter chamber formation signal is received, the direction switching valve of the pressure oil device 50 sends the pressure oil to the filter frame drive unit 36 via the pressure oil pipes 503 and 504.

  Further, when the low pressure pump control unit 614 and the high pressure pump control unit 615 receive the stop confirmation signal and detect that the dehydration end button (not shown) is pressed, the dehydration processing device control unit 611 switches the direction of the pressure oil device 50. A filter open signal is transmitted to the valve via signal line 606. When the filter chamber formation signal is received, the direction switching valve of the pressure oil device 50 finishes sending the pressure oil to the filter frame drive unit 36.

  The slurry density storage unit 612 stores slurry density information corresponding to the slurry density signal inside the slurry tank 10 transmitted from the density meter 14 via the signal line 601.

  When the low pressure driving time determination unit 613 detects pressing of a dehydration start button (not shown), the slurry density information in the slurry tank 10 stored in the slurry density storage unit 612 and the given information stored in the storage unit 62 are stored. Compare with threshold density information. Based on the comparison result, the low-pressure driving time determination unit 613 determines a low-pressure driving time that is a time from when the low-pressure pump is started to when the high-pressure pump is started. When the slurry density in the slurry tank 10 is smaller than the threshold density, the low pressure implantation time determination unit 613 determines the first implantation time stored in the storage unit 62 as the low pressure implantation time. On the other hand, when the slurry density inside the slurry tank 10 is larger than the threshold density, the low pressure implantation time determination unit 613 determines the second implantation time stored in the storage unit 62 as the low pressure implantation time. The second driving time is shorter than the first driving time.

  FIG. 6 is a diagram illustrating the relationship between the slurry density and the dehydration time in the dehydration apparatus 1. In FIG. 6, the curve indicated by the solid line is a curve showing the relationship between the slurry density and the dehydration time when the low pressure implantation time is 20 minutes. That is, in the dehydration process in the curve indicated by the solid line, the high pressure pump 20 is activated after 20 minutes have elapsed since the low pressure pump 15 was activated. Moreover, the curve shown with a broken line is a curve which shows the relationship between a slurry density when low pressure implantation time is 30 minutes, and dehydration time. That is, in the dehydration process in the curve indicated by the broken line, the high pressure pump 20 is activated after 30 minutes have elapsed since the low pressure pump 15 was activated. The dehydration time is the time from when the low pressure pump 15 is activated until the pressure inside the filter chamber of the high pressure filter press type dehydrator 30 reaches 4 [MPa].

  When the slurry density is low, the dehydration time is shorter when the low pressure implantation time indicated by the broken line is 30 minutes than when the low pressure implantation time indicated by the solid line is 20 minutes. For example, when the slurry density indicated by the arrow A is 1.10 [g / cm 3], the dehydration time is 10 minutes when the low pressure implantation time is 30 minutes than when the low pressure implantation time is 20 minutes. About shortened.

  On the other hand, when the slurry density is high, the dehydration time is shorter when the low pressure implantation time is 20 minutes than when the low pressure implantation time is 30 minutes. For example, when the slurry density indicated by the arrow B is 1.18 [g / cm 3], the dehydration time is 5 minutes when the low pressure implantation time is 20 minutes than when the low pressure implantation time is 30 minutes. About shortened.

  Further, at a slurry density of 1.12 [g / cm 3] indicated by the arrow C, the dehydration time is the same when the low pressure implantation time is 20 minutes and when the low pressure implantation time is 30 minutes.

In the example shown in FIG. 6, the low pressure implantation time determination unit 613 sets the threshold density to 1.12 [g / cm 3], sets the first implantation time to 30 minutes, and sets the second implantation time to 20 minutes. Set to With such setting, the dehydration time of the dehydration apparatus 1 can be shortened.

  The low-pressure pump control unit 614 transmits an activation command signal to the low-pressure pump 15 when the low-pressure driving time determination unit 613 determines the low-pressure driving time. The low-pressure pump control unit 614 transmits a stop command signal to the low-pressure pump 15 when the filtration chamber pressure determination unit 616 determines that the pressure inside the filtration chamber is 4 [MPa] or more.

  The high pressure pump control unit 615 measures the time from when the activation confirmation signal indicating that the low pressure pump 15 is activated is received from the low pressure pump 15 until the low pressure implantation time elapses. When the low pressure driving time has elapsed since the start confirmation signal was received, the high pressure pump control unit 615 starts transmitting the first and second high pressure pump discharge signals to the pressure oil device 50 in order to start the high pressure pump 20. To do. When the high pressure pump controller 615 determines that the pressure inside the filter chamber 616 is 4 [MPa] or higher, the first and second high pressure pump discharge signals to the pressure oil device 50 are determined. The transmission is terminated and the high-pressure pump 20 is stopped.

  The filter chamber pressure determination unit 616 receives a filter chamber pressure signal corresponding to the pressure inside the filter chamber transmitted from the pressure gauge 35 of the high-pressure filter press dehydrator 30, and receives the filter pressure of the high-pressure filter press dehydrator 30. It is determined whether or not the pressure inside the chamber exceeds 4 [MPa].

  FIG. 7 is a diagram illustrating an example of a dehydration process flow of the dehydration apparatus 1.

  First, in step S <b> 101, the dehydration processing device controller 611 detects pressing of a dehydration start button (not shown), transmits a filter chamber formation signal to the direction switching valve of the pressure oil device 50, and starts dehydration processing. The pressure oil device 50 that has received the filter chamber formation signal sends the pressure oil to the filter frame drive unit 36 of the high-pressure filter press-type dewatering device 30. When pressure oil is press-fitted into the filter frame drive unit 36, the plurality of filter frames 31 of the high-pressure filter press-type dewatering device 30 are arranged in close contact with each other, and a plurality of filter chambers are formed between adjacent filter frames 31. Is done.

  Next, in step S <b> 102, the slurry density storage unit 612 stores the slurry concentration information corresponding to the slurry density signal inside the slurry tank 10 transmitted from the density meter 14 via the signal line 601.

  Next, in step S103, the low pressure implantation time determination unit 613 determines the low pressure implantation time by comparing the slurry density information stored in the slurry density storage unit 612 with the threshold density information. When the slurry density is smaller than the threshold density, the low pressure implantation time determination unit 613 determines the first implantation time as the low pressure implantation time. On the other hand, when the slurry density inside the slurry tank 10 is larger than the threshold density, the low pressure implantation time determination unit 613 determines the second implantation time shorter than the first implantation time as the low pressure implantation time.

  Next, in step S <b> 104, the low pressure pump control unit 614 transmits a start command signal to the low pressure pump 15 to start the low pressure pump 15.

  Next, in step S <b> 105, the high pressure pump control unit 615 transmits a start command signal to the high pressure pump 20 after the low pressure driving time has elapsed, and starts the high pressure pump 20.

  Next, in step S106, the filtration chamber pressure determination unit 616 determines whether or not the pressure inside the filtration chamber of the high-pressure filter press dehydrator 30 exceeds 4 [MPa].

  In step S106, when the filtration chamber pressure determination unit 616 determines that the pressure inside the filtration chamber of the high-pressure filter press dehydrator 30 does not exceed 4 [MPa], the process returns to step S106. In Step S106, when the filter chamber pressure determination unit 616 determines that the pressure inside the filter chamber of the high-pressure filter press dehydrator 30 exceeds 4 [MPa], the process proceeds to Step S107.

  Next, in step S <b> 107, the low pressure pump control unit 614 transmits a stop command signal to the low pressure pump 15 to stop the low pressure pump 15. The high pressure pump control unit 615 transmits a stop command signal to the high pressure pump 20 to stop the high pressure pump 20.

  In step S108, the dehydration processing device control unit 611 detects that a dehydration end button (not shown) is pressed, transmits a filter chamber opening signal to the direction switching valve of the pressure oil device 50, and ends the dehydration processing. The pressure oil device 50 that has received the filter chamber opening signal ends the sending of the pressure oil to the filter frame drive unit 36 of the high-pressure filter press-type dewatering device 30. When the pressure oil is discharged from the filter frame driving unit 36, the plurality of filter frames 31 of the high-pressure filter press-type dewatering device 30 are arranged at predetermined intervals, and the generated dewatered cake 303 is the first dewatered cake cake. It falls on the belt conveyor 41.

  When the slurry density of the slurry tank 10 is lower than the predetermined threshold density, the dehydration time is shortened if the low pressure implantation time is increased. On the other hand, when the slurry density in the slurry tank 10 is higher than the predetermined threshold density, the dehydration time is shortened if the low pressure implantation time is shortened. The dehydration apparatus 1 determines whether or not the slurry density of the slurry tank 10 is higher than a predetermined threshold density, and determines the low-pressure driving time based on the determination result, so that the dehydration time can be shortened. . Further, since the dehydration apparatus 1 can select a low pressure implantation time based on the slurry density of the slurry tank 10, it prevents the water hammer from being generated in the filter chamber of the high pressure filter press type dehydrator 30. Furthermore, since the dehydration apparatus 1 can shorten the dehydration time, power consumption can be reduced.

  Further, in the dehydration processing apparatus 1, since the low-pressure driving time is determined based on the slurry density detected before the low-pressure pump is started, it is not necessary to consider the variation in the slurry density of the low-pressure driving time, and the determination process is simplified. become.

  In the dehydration apparatus 1, the threshold density is a density at which the dehydration time when the low pressure implantation time is the first implantation time and the dehydration time when the low pressure implantation time is the second implantation time are equal. However, it may be determined based on other factors than the dehydration time. For example, the threshold density may be a density at which the power consumption when the low voltage implantation time is the first implantation time and the power consumption when the low voltage implantation time is the second implantation time are equal. In the dehydration apparatus 1, an example in which the first driving time is 30 minutes and the second driving time is 20 minutes will be described. If the second driving time is shorter than the first driving time, the first driving time will be described. The second driving time may be set to another time.

  In the dehydration apparatus 1, when the high-pressure pump 20 is in operation, the slurry that is discharged from the low-pressure pump 15 but is not sucked into the high-pressure pump 20 returns to the slurry tank 10 via the return valve 205. The pump 15 may be inverter controlled. By controlling the low-pressure pump 15 with an inverter, the discharge amount of the low-pressure pump 15 can be controlled to be equal to the discharge amount of the high-pressure pump 20, so that the return valve 205 can be omitted and the power saving of the dehydration apparatus 1 is further reduced. it can.

  In the dehydration apparatus 1, the high pressure pump 20 is connected in series to the low pressure pump 15, but the high pressure pump 20 may be connected in parallel to the low pressure pump 15. In this case, the low-pressure pump 15 stops after the low-pressure driving time has elapsed, and after the low-pressure driving time has elapsed, the high-pressure pump 20 alone presses the slurry into the filter chamber of the high-pressure filter press dehydrator 30. The high-pressure pump 20 is a hydraulically driven pump, but may be an electrically driven pump having a high discharge pressure.

  In the dehydration apparatus 1, when the pressure inside the filter chamber of the high-pressure filter press-type dehydrator 30 reaches 4 [MPa], it is determined that the dehydration process is finished, but the pressure inside the filter chamber is 4 The end of the dehydration process may be determined when a value less than [MPa] is reached. Alternatively, the end of the dehydration process may be determined when the pressure inside the filter chamber reaches a value greater than 4 [MPa]. The end of the dehydration process may be determined by another algorithm. For example, the end of the dehydration process may be determined from the relationship between the capacity of the filter chamber of the high-pressure filter press-type dehydrator 30 and the capacity of the dehydrated cake calculated from the density detected by the density meter 14 and the dehydration time. .

  In the dehydration apparatus 1, the low pressure implantation time determination unit 613 uses a single threshold density for comparison with the slurry density inside the slurry tank 10, but a plurality of threshold densities are used. May be. By using a plurality of threshold densities for comparison with the slurry density inside the slurry tank 10, the dehydration time can be further shortened.

  FIG. 8A is a diagram illustrating an example of fluctuations in the slurry density of the slurry tank 10. The horizontal axis of the graph shown in FIG. 8A is the operating day of the dehydration processing system, and the vertical axis is the slurry density of the slurry tank 10.

The slurry density of the slurry tank 10 varies in the range of 1.15 [g / cm ³ ] to 1.20 [g / cm ³ ]. The fluctuation of the slurry density of the slurry tank 10 does not depend on the time zone, but depends on the type of dredged soil such as dredged sea area, dredging method, and the like.

  FIG. 8B is a diagram showing an example of a change with time of current consumption of the dehydration apparatus 1. The horizontal axis of the graph shown in FIG. 8B is the dehydration time for one cycle, and the vertical axis is the instantaneous current value of the current consumed by the dehydration processing apparatus 1.

  Since the low-pressure driving time of the dehydrating apparatus 1 is 20 minutes, the low-pressure driving starts 3 minutes after the dehydrating process starts, and the low-pressure driving ends 23 minutes after the dehydrating process 1 starts. doing.

  The maximum current value of the dehydrating apparatus 1 in the low-pressure driving is 120 [A], and the minimum current value is 80 [A]. In the low pressure driving, the current for driving the low pressure pump 15 is dominant.

The maximum current value of the dehydration apparatus 1 in high-pressure driving is 160 [A], and the minimum current value is 140 [A]. In the high-pressure driving, the current that drives the low-pressure pump 15 and the high-pressure pump 20 is dominant.

  FIG. 8C is a diagram illustrating an example of the relationship between the slurry density of the slurry tank 10 and the power consumption of the dehydration apparatus 1. The horizontal axis of the graph shown in FIG. 8C is the slurry density of the slurry tank 10, and the vertical axis is the amount of power consumed by the dehydration apparatus 1. In FIG.8 (c), the straight line shown as a continuous line is a curve which shows the relationship between a slurry density when low voltage | pressure implantation time is 20 minutes, and electric energy. Moreover, the straight line shown with a broken line is a curve which shows the relationship between a slurry density when low voltage | pressure implantation time is 30 minutes, and electric energy.

When the slurry density is in the range of 1.150 [g / cm ³ ] to 1.175 [g / cm ³ ], the low pressure implantation time is 30 minutes than the low pressure implantation time is 20 minutes. The amount of power is small. On the other hand, when the slurry density is in the range of 1.175 [g / cm ³ ] to 1.200 [g / cm ³ ], the low pressure implantation time is 20 minutes than the low pressure implantation time is 30 minutes. However, power consumption is small.

From this, when the slurry density is in the range of 1.150 [g / cm ³ ] to 1.175 [g / cm ³ ], the low pressure implantation time is set to 30 minutes, and the slurry density is 1.175 [g / cm ³ ]. In the range of ˜1.200 [g / cm ³ ], the low pressure implantation time is set to 20 minutes.

  By setting the low-pressure driving time to be selected in this way, the power consumption of the dehydrating apparatus 1 is reduced by 3.5%.

DESCRIPTION OF SYMBOLS 1 Dehydration processing apparatus 10 Slurry tank 15 Low pressure pump 20 High pressure pump 30 High pressure filter press type dehydrator 60 Control part

Claims (5)

Slurry tank for storing slurry contained in sludge,
A density meter for detecting the density of the slurry stored in the slurry tank;
A high-pressure filter press-type dewatering device having a filter chamber that can be opened and closed, and dewatering the slurry in the filter chamber to produce a dewatered cake;
A low-pressure pump for transferring the slurry stored in the slurry tank to the filter chamber;
In order to pressurize the slurry stored in the slurry tank at a discharge pressure higher than the discharge pressure of the low-pressure pump and press-fit it into the filter chamber, the low-pressure pump is started after the low-pressure driving time has elapsed. A high-pressure pump that
A control unit that controls the low-pressure pump and the high-pressure pump, compares the detected slurry density with a threshold density, and determines the low-pressure driving time based on the comparison ;
When the slurry density is smaller than a predetermined threshold density, the control unit determines the low pressure implantation time as a first implantation time, and when the slurry density is larger than the predetermined threshold density. The dehydration apparatus is characterized in that the low pressure implantation time is determined to be a second implantation time shorter than the first implantation time . The threshold density is a density at which a dehydration time when the low pressure implantation time is the first implantation time and a dehydration time when the low pressure implantation time is the second implantation time are equal. Item 2. The dehydrating apparatus according to Item 1 . The dehydration processing apparatus according to claim 1 or 2 , wherein the slurry density is a density detected before the low-pressure pump is started. Detect the density of the slurry contained in the sludge stored in the slurry tank,
Comparing the detected slurry density with the threshold density, based on the comparison result, a low-pressure pump is started to transfer the slurry stored in the slurry tank to the filter chamber of the high-pressure filter press dehydrator. From this, the low pressure driving time, which is the time until the high pressure pump that pressurizes the slurry stored in the slurry tank with a discharge pressure higher than the discharge pressure of the low pressure pump and press-fits into the filter chamber, is determined,
Start the low pressure pump,
Starting the high-pressure pump after the low-pressure driving time has elapsed since the low-pressure pump was started ,
The low pressure implantation time is determined when the slurry density is smaller than a predetermined threshold density, the low pressure implantation time is determined as the first implantation time, and the slurry density is the predetermined threshold density. Is larger than the first driving time, the low driving time is determined as the second driving time shorter than the first driving time . Detect the density of the slurry contained in the sludge stored in the slurry tank,
Comparing the detected slurry density with the threshold density, based on the comparison result, a low-pressure pump is started to transfer the slurry stored in the slurry tank to the filter chamber of the high-pressure filter press dehydrator. From this, the low pressure driving time, which is the time until the high pressure pump that pressurizes the slurry stored in the slurry tank with a discharge pressure higher than the discharge pressure of the low pressure pump and press-fits into the filter chamber, is determined,
Start the low pressure pump,
A process of starting the high-pressure pump after the low-pressure driving time has elapsed since the low-pressure pump was started;
The low pressure implantation time is determined when the slurry density is smaller than a predetermined threshold density, the low pressure implantation time is determined as the first implantation time, and the slurry density is the predetermined threshold density. Is greater than the first driving time , the computer executes a process including determining a low pressure driving time at a second driving time shorter than the first driving time .

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