JP4547103B2 - Operation method of high pressure pump of filter press type dehydrator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for operating a high-pressure pump of a filter press type dehydrator for producing a cake by dewatering a slurry stock solution containing dredging, sewage sludge, construction residual soil, and the like using a filter press.
[0002]
[Prior art]
Conventionally, as a method of separating and reducing the amount of water from undiluted liquids (also called slurries) consisting of soil and sand from rivers and dams, sewage sludge treated from domestic wastewater, residual soil containing water generated during construction work, etc. Press dehydrators are widely used in various industries.
The filter press-type dewatering device is a low-pressure, large-capacity centrifugal pump that first feeds the stock solution into the filter chamber in the filter cloth of the filter press, quickly fills the filter chamber, and then has a reciprocating cylinder. By switching to a high-pressure small-capacity pump (hereinafter referred to as a high-pressure pump), the stock solution is pumped, and the filtration time of the stock solution is shortened to improve the filtration efficiency.
However, the stop timing of the high-pressure pump in this filtration step greatly affects the moisture content of the cake produced by filtering water from the stock solution.
In particular, when the cake dehydrated by filtration is used as a landfill or soil improvement material, it is desired that the amount of water contained in the cake be uniform, and the high-pressure pump of the filter press dehydrator is stopped. It is important to control the timing appropriately.
Therefore, in order to make the moisture content of the dehydrated cake uniform, as a method of adjusting the stop time of the high pressure pump (end time of the dehydration treatment), after reaching a set filtration pressure, a low pressure centrifugal pump is used. Based on the set time set as the fixed time from the start of filling the stock solution to the stop of the high-pressure pump, for example, the operator finishes filtration (dehydration) or automates by setting the set time with a timer Then, after reaching the filtration time, the dehydration is terminated.
However, in this operation method, as shown in FIG. 5, for example, in the case of a stock solution A whose properties have changed and has become easy to be dehydrated, as a stock solution to be dehydrated, a set value (dehydration time) for stopping the high-pressure pump is obtained. Prior to the end time), the cumulative drainage of the cake reaches the target value.
Furthermore, in the case of the stock solution C in which the properties of the stock solution have changed and it has become difficult to filter, at the time of the set value of the dehydration time, the total amount is higher than that of the stock solution B having the standard stock solution characteristics with no change in properties at the initial slurry. Since the amount of drainage decreases, the moisture content of the cake tends to increase.
That is, when a stock solution whose properties change over time is used, the operation with a certain set time causes a change in the total drainage amount, making it difficult to make the water content of the dehydrated cake uniform. .
As a countermeasure, there is a method described in Japanese Patent No. 2936411. That is, the mass flow rate and density of the stock solution supplied to the filter press type dehydrator are detected in real time, and the dry soil content is calculated based on the detected value, and the calculated dry soil content is set in advance. The moisture content of the cake is calculated based on the true specific gravity of the soil particles, and the moisture content of the cake is compared with the target moisture content of the cake. When the moisture content of the cake after dehydration is lower than the target moisture content, the operation of the filter press is continued, and when the moisture content of the cake after dehydration exceeds the target moisture content, the operation of the filter press is stopped. Thus, the water content ratio of the dehydrated cake is controlled, and the water content of the cake is accurately grasped to improve the dewatering efficiency.
[0003]
[Problems to be solved by the invention]
However, the method described in Japanese Patent No. 2936411 has the following problems.
There are many types of sludge, residual soil, etc., and when applied to the dehydration of a stock solution whose properties change over time, it takes time and effort to set the dehydration conditions in real time. .
For example, in the case of dredged sludge, the viscosity, solid particle size, presence or absence of inclusions, etc., vary greatly depending on the dredging location. In the evening, the properties vary irregularly.
In order to dehydrate a stock solution whose properties greatly change, various instruments are required for real-time measurement of the mass flow rate and density of the stock solution, and based on the accumulated dry soil content and the true specific gravity of the soil particles set in advance. It takes time and effort to obtain the moisture content of the cake. Furthermore, when the filter press type dehydrating apparatus is operated, there is a problem that it requires experience for the operation and is not general-purpose as a practical technique.
[0004]
The present invention has been made in view of such circumstances, and simplifies the equipment such as the measuring equipment of the filter press type dehydrating device, facilitates its operation, and dredged sludge and sewage sludge whose properties are easily changed in time series. Of the high pressure pump of the filter press type dehydrator that can make the moisture content of the cake after dewatering residual soil including water generated in construction work uniform and can easily identify the abnormal state of the filter press The purpose is to provide a driving method.
[0005]
[Means for Solving the Problems]
The operation method of the high-pressure pump of the filter press type dehydrator according to the present invention in accordance with the above object is that the stock solution is pumped by a low pressure pump at the initial stage of dehydration using the filter press type dehydrator, and then has a reciprocating cylinder. In the operation method of the high pressure pump of the filter press type dehydrator that pumps the stock solution from the high pressure pump to the filter press type dehydrator and dehydrates the stock solution to produce a cake,
The movement time of the piston of the high-pressure pump for pumping the stock solution is set in advance, and when the movement time of the piston of the high-pressure pump becomes longer than the set movement time of the piston of the high-pressure pump, the high-pressure pump The operation is stopped and the dehydration is completed . Further, after the moving time of the piston of the high-pressure pump becomes long, the moving time of the piston of the high-pressure pump becomes short.
With this method, the moisture content of the dehydrated cake is determined by the travel time of the piston of the high-pressure pump that supplies the stock solution. Therefore, even if the viscosity of the stock solution or the particle size of the solid changes over time, the moisture content of the cake remains uniform. And can be used for landfills, soil improvement materials and the like.
[0006]
Here, in the operation method of the high pressure pump of the filter press type dehydrator according to the present invention, the moving time of the piston of the high pressure pump is converted into the moving speed of the piston, and the moving time of the piston of the high pressure pump becomes longer. After that, instead of determining that the moving time of the piston of the high-pressure pump is shortened, the moving speed of the piston of the high-pressure pump is increased after the moving speed of the piston of the high-pressure pump is decreased. The case can also be determined as an abnormal state .
This simplifies the equipment such as the measuring equipment of the filter press-type dewatering device, and the water content of dewatered cake, such as dredged soil, sewage sludge, and soil containing water generated during construction work, whose properties are likely to change over time Can be made uniform, and the operation thereof can be facilitated.
[0008]
Then, it is possible to detect anomalies caused by breakage of the filter cloth of the filter press type dehydrator, poor sealing of the filtration chamber, or the like.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
FIG. 1 is an overall view of a filter press dehydrator applied to a method for operating a high pressure pump of a filter press dehydrator according to an embodiment of the present invention, FIG. 2 is a conceptual diagram of the high pressure pump, and FIG. FIG. 4 is a graph showing the relationship between time and accumulated drainage amount, and FIG. 4 is a graph showing the relationship between dehydration time and piston moving time (moving speed).
As shown in FIGS. 1 and 2, a filter press dehydrator 10 used in a method for operating a high pressure pump of a filter press dehydrator according to an embodiment of the present invention uses a stock solution (also called slurry) as a filter press. 11, a high-pressure pump 12 that pumps (feeds) the oil, a hydraulic unit 13 that communicates with the high-pressure pump 12 and reciprocates the high-pressure pump 12 , a suction pump 14 that supplies the stock solution to the high-pressure pump 12 , and a feed A vortex-type low-pressure pump (not shown) is included.
Furthermore, the filter press 11 has a plurality of filtration chambers 15 formed by adjacent filter plates lined with a filter cloth, and a filtration receptacle (not shown) for draining filtered water obtained by filtering the stock solution is located below the filter press 11. Has been placed.
[0010]
The high pressure pump 12 repeats a reciprocating operation, and a hydraulic cylinder 21 including a piston 21a having limit switches 21b and 21c, which is an example of a device for detecting a reciprocating end position, and muddy water communicating with the hydraulic cylinder 21. Pumps 22 and 23 are provided.
The muddy water pump 22 has a hydraulic chamber 24 partitioned by a rubber film 22a, an intermediate chamber 25 partitioned by a rubber film 22a and a rubber film 22b, filled with water and antifreeze liquid, and a stock solution partitioned by a rubber film 22b and a discharge valve 27. In addition, a suction and discharge chamber 26 for a stock solution to be sucked or discharged is provided by switching the suction valve 28. Similarly, the muddy water pump 23 has a hydraulic chamber 29, a rubber film 23a and a rubber film partitioned by a rubber film 23a. An intermediate chamber 30 containing water and antifreeze liquid partitioned by 23b, and a suction / discharge chamber 31 of the raw liquid for sucking or discharging the stock solution by switching between the discharge valve 32 and the suction valve 33 partitioned by the rubber film 23b. .
A muddy water discharge pipe 35 for supplying the stock solution to the filter press 11 is connected to the pipe 34 connecting the discharge valve 27 and the discharge valve 32, and the stock solution is connected to the pipe 36 connecting the suction valve 28 and the suction valve 33. A mud suction pipe 37 for suction is connected.
[0011]
Next, a method for operating the high-pressure pump of the filter press dehydrator according to the embodiment of the present invention will be described using the filter press dehydrator 10.
The sludge produced during dredging was primarily precipitated, and the generated stock solution was fed to the filter chamber 15 of the filter press 11 by operating a vortex low-pressure pump.
Thereafter, the hydraulic unit 13 is operated to push the piston 21a of the hydraulic cylinder 21 of the high-pressure pump 12 in the direction indicated by the arrow in FIG.
By pushing the piston 21a, hydraulic pressure is applied to the hydraulic chamber 24 of the muddy water pump 22, as shown in FIG. This oil pressure is transmitted to the intermediate chamber 25, and the rubber film 22 b forming the intermediate chamber 25 is pushed into the suction / discharge chamber 26 to swell, and the stock solution sucked into the suction / discharge chamber 26 passes through the discharge valve 27 and the pipe 34. It is extruded through the muddy water discharge pipe 35 and is pumped (supplied) to the filtration chamber 15 of the filter press 11.
On the other hand, when the piston 21a of the hydraulic cylinder 21 operates in the direction of the arrow in the figure, the muddy water pump 23 is on the suction side, the hydraulic pressure in the hydraulic chamber 29 provided in the muddy water pump 23 is released, and the rubber film 23a is on the hydraulic chamber 29 side. Dent. Then, the rubber film 23 b forming the intermediate chamber 30 is also dented and a suction force is generated in the suction / discharge chamber 31.
Then, due to the suction force generated in the suction / discharge chamber 31, the stock solution is sucked into the suction / discharge chamber 31 via the suction valve 33 via the pipe 36 from the muddy water suction pipe 37.
[0012]
The operation of the piston 21a of the hydraulic cylinder 21 is a reciprocating operation, and since the operation in the direction opposite to the direction of the arrow is alternately repeated, the muddy water pump 22 and the muddy water pump 23 alternately supply the stock solution at a high pressure. , Can be continuously fed to the filtration chamber 15 of the filter press 11.
And only the water | moisture content is filtered from the undiluted | stock solution sent to the filtration chamber 15 with the filter cloth lined on the filter board, The cake which consists of solid content and residual water produces | generates.
The filtered water is discharged out of the system from the drainage receptacle.
[0013]
The stock solution that is fed to the filtration chamber 15 of the filter press 11 by this high-pressure pump 12 and dehydrated has different viscosity depending on the surface layer portion, middle layer, lower layer, etc. The diameter, the amount and type of inclusions that are impurities, and the like change.
As shown in FIG. 3, when the accumulated drainage amount with the passage of the dehydration time of the stock solution is viewed, for example, in the case where the stock solution is a stock solution B having an ordinary dehydration property (initial slurry having no change in properties) B, the dehydration time over, although total drainage amount increases, it fixed the time after which, the tendency of increase in the total drainage volume change (rate of increase is reduced), and the inclination (alpha ₀₎ is abruptly reduced.
However, in the case of undiluted solution (slurry after property change) A that changes its properties such as sand and mud, the accumulated drainage amount increases rapidly with the passage of the dehydration time. The decrease change (decrease in the rate of increase) occurs earlier than the stock solution B. At this time, the inclination (α ₂ ) becomes small.
On the other hand, in the case of undiluted stock solution (slurry after property change) C whose properties have changed and viscosity and solid content particle size have become small, the cumulative drainage amount gradually increases with the passage of the dehydration time. , The decrease change of the accumulated drainage amount (the rate of increase decreases) occurs later than the stock solution B. At this time, the inclination (α ₁ ) becomes small.
Therefore, it is necessary to set the point (slope) at which the amount of decrease in the accumulated drainage amount changes (decrease in the rate of increase) to a constant value, that is, to end the dehydration with the amount of change in the drainage amount constant. At the time of dehydration, the filtration resistance of the cake is made constant and the dehydration is terminated, so that the solid density in the cake can be made constant.
For this reason, the solid density in the cake is obtained by obtaining the inflection points at which the respective inclinations (α ₀ ), inclinations (α ₁ ), and inclinations (α ₂ ) are the same, using a commonly used calculation formula. However, it takes time to set conditions and to operate when there are many changes in the type and properties of the stock solution.
[0014]
Therefore, the filtration resistance of the cake is the resistance of the muddy water pumps 22 and 23 for feeding the stock solution to the filtration chamber 15 of the filter press 11 at a high pressure, and the piston 21a of the hydraulic cylinder 21 for feeding the stock solution reciprocates. It is utilized that it is reflected in the moving time or the moving speed of the reciprocating motion.
As shown in FIG. 4, the moving time or moving speed of the reciprocating operation of the piston 21 a of the hydraulic cylinder 21 is as follows: from the initial stage to the middle stage of feeding the stock solution when feeding the stock solution to the filtration chamber 15 of the filter press 11. Although the movement time is short or the movement speed is high, at the end when the inclination is small, the movement time of the piston 21a is abruptly long or the movement speed is abruptly slowed.
That is, in the case of a stock solution A that is easily dehydrated, such as sand and mud, in the case of a stock solution B that has a normal dehydration property in which the properties of the stock solution do not change, the stock solution C that is difficult to dehydrate due to a small change in viscosity or a solid-containing particle size. In this case, the dehydration is performed by setting the moving time of the piston 21a of the hydraulic cylinder 21 to a predetermined set value, and the end of dehydration is determined when the moving time of the piston 21a becomes longer than the set value, or The dehydration is performed by setting the moving speed of the piston 21a of the hydraulic cylinder 21 to a constant set value, and when the moving speed of the piston 21a becomes slower than the set value, the end of the dehydration is determined to generate the dehydration. The water content of the cake can be made uniform. The time of the reciprocating operation of the piston 21a or the pushing operation on one side can be obtained by measuring the required time of contact with the limit switches 21b and 21c.
Further, for each moving time of the piston 21a of the hydraulic cylinder 21, the cake dehydration rate data described above is obtained in advance, and based on this value, the type of stock solution is selected to determine the dehydration rate, and the filter press 11 You can also drive.
[0015]
Further, in the operation method of the high pressure pump of the filter press type dehydrator according to the present embodiment, the moving time (moving speed) of the piston 21a of the hydraulic cylinder 21 is managed, so that the filter cloth is damaged or the filter chamber 15 has a poor seal. When the above occurs, the moving time of the piston 21a of the hydraulic cylinder 21 is shortened rapidly or the moving speed is increased. Therefore, the change such as the breakage of the filter cloth and the sealing failure of the filter chamber 15 is caused early due to this change. Can be detected. That is, after the movement time of the piston 21a of the hydraulic cylinder 21 provided in the high-pressure pump 12 becomes longer, the case where the movement time of the piston 21a of the hydraulic cylinder 21 becomes shorter is determined as an abnormal state. When the moving time of the piston 21a of the hydraulic cylinder 21 is converted into the moving speed of the piston 21a, the moving speed of the piston 21a of the hydraulic cylinder 21 provided in the high-pressure pump 12 becomes slow, and then the moving of the piston 21a of the hydraulic cylinder 21 The case where the speed is increased is determined as an abnormal state.
And when abnormality is detected, supply of the undiluted | stock solution to the filter press 11 is stopped urgently, damage to an apparatus and maintenance of a workplace can be performed.
The cake thus dehydrated is transported by a truck or the like and used as a landfill material or a soil improvement material.
[0016]
【Example】
Next, an embodiment of a method for operating the high pressure pump of the filter press type dehydrator will be described.
For a stock solution containing 30% by weight of crushed solids, a stock solution A that is easily dewatered, such as sand and mud, a stock solution B in which the stock solution has a normal dehydration property, a viscosity whose properties have changed, and a solid-containing particle size are small. Each of the undiluted undiluted concentrates C was used, and this undiluted solution was supplied to the filter chamber of the filter press by operating a vortex low-pressure pump, and then a piston having an operating length (movement distance) of 400 mm via a hydraulic unit. The high-pressure pump was operated by operating the hydraulic cylinder having No., and the stock solution was pumped into the filtration chamber of the filter press, and the moving time of the piston of the hydraulic cylinder was set to 30 seconds.
As a result, when the stock solution was supplied to the filtration chamber by this high-pressure pump, the piston travel time (push-out stroke) from the beginning to the middle of the dehydration elapsed time was 3 seconds, but at the end of the dehydration, the piston of the hydraulic cylinder Since the moving time was 30 seconds and the moving time of the hydraulic cylinder reached the set value, dehydration was terminated at this point.
And the cake produced | generated from the stock solution A, the cake produced | generated from the stock solution B, the cake produced | generated from the stock solution C were taken out, respectively, As a result of measuring the moisture content of each cake, the cake of the stock solution A, the cake of the stock solution B, the stock solution C All of the cakes had a water content of 20% by weight and could be made uniform.
[0017]
In addition, the stock solution was fed to the filtration chamber by a high pressure pump, and the high pressure pump was operated at a piston moving speed of 133.3 mm / second (400 mm / 3 second). After moving to 16 mm / sec (400 mm / 25 sec) and again exceeding 16 mm / sec, it was judged abnormal and the operation was stopped. Damage could be confirmed.
[0018]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and all changes in conditions and the like that do not depart from the gist are within the scope of the present invention.
For example, for the detection of the position of the piston of a hydraulic cylinder, in addition to the limit switch, commonly used devices such as an optical sensor and a magnetic sensor can be adopted, and an arithmetic unit that calculates the movement time and movement speed from the detected position Also, a computer or the like can be used.
Furthermore, using the fact that the trend of increase in cumulative drainage (rate of increase) changes, the inflection point whose slope changes rapidly and small is input to the computer, and this accumulated data is stored from the accumulated data. It is also possible to set a dehydration processing time by selecting a stock solution corresponding to the obtained data.
[0019]
【The invention's effect】
In the operation method of the high-pressure pump of the filter press type dehydrator according to claim 1 or 2, in the initial stage of dehydration using the filter press type dehydrator, the stock solution is pumped by a low pressure pump, and thereafter a reciprocating cylinder is provided. In the operation method of the filter press type dehydrator that pumps the stock solution from the high pressure pump to the filter press dehydrator and dehydrates the stock solution to produce a cake, the moving time of the piston of the high pressure pump that pumps the stock solution is set in advance. When the moving time of the piston of the high-pressure pump becomes longer than the set moving time of the piston of the high-pressure pump, the operation of the high-pressure pump is stopped and the dehydration is completed. Simplified equipment, making it easy to operate, dredged soil, sewage sludge, construction work whose properties are easy to change over time It can be made uniform water content of the cake after the dehydration of such waste soil containing water generated.
[0021]
And, if the moving time of the piston of the high-pressure pump becomes long after the moving time of the piston of the high-pressure pump becomes long, it is judged as an abnormal state, so that abnormalities such as breakage of the filter cloth and poor sealing of the filtration chamber are detected. And the operation of the dehydrator can be performed stably. In addition, the workplace can be safe and the environment can be protected.
[0022]
In the operation method of the high-pressure pump of the filter press type dehydrator according to claim 2, it is determined that an abnormal state occurs when the moving speed of the piston of the high-pressure pump increases after the moving speed of the piston of the high-pressure pump becomes slow. Therefore, it is possible to accurately detect abnormality such as breakage of the filter cloth and defective sealing of the filtration chamber, and the operation of the dehydrating apparatus can be performed more stably.
[Brief description of the drawings]
FIG. 1 is an overall view of a filter press dehydrator applied to a method of operating a high pressure pump of a filter press dehydrator according to an embodiment of the present invention.
FIG. 2 is a conceptual diagram of the high-pressure pump.
FIG. 3 is a graph showing the relationship between the dehydration time and the accumulated drainage amount.
FIG. 4 is a graph showing the relationship between dehydration time and piston movement time.
FIG. 5 is a graph showing the relationship between the dewatering time and the accumulated drainage amount in the conventional stock solution dewatering method.
[Explanation of symbols]
10: filter press type dehydrator, 11: filter press, 12: high pressure pump, 13: hydraulic unit, 14: suction pump, 15: filtration chamber, 21: hydraulic cylinder, 21a: piston, 21b: limit switch, 21c: limit Switch, 22: Muddy water pump, 22a: Rubber membrane, 22b: Rubber membrane, 23: Muddy water pump, 23a: Rubber membrane, 23b: Rubber membrane, 24: Hydraulic chamber, 25: Intermediate chamber, 26: Suction / discharge chamber, 27: Discharge valve, 28: suction valve, 29: hydraulic chamber, 30: intermediate chamber, 31: suction / discharge chamber, 32: discharge valve, 33: suction valve, 34: piping, 35: muddy water discharge tube, 36: piping, 37: Mud suction pipe

Claims (2)

At the initial stage of dehydration using a filter press type dehydrator, the stock solution is pumped by a low pressure pump, and then the stock solution is pumped from the high pressure pump having a reciprocating cylinder to the filter press type dehydrator to dehydrate the stock solution and cake. In the operation method of the high pressure pump of the filter press type dehydrator for producing
The movement time of the piston of the high-pressure pump that pumps the stock solution is set in advance, and when the movement time of the piston of the high-pressure pump becomes longer than the set movement time of the piston of the high-pressure pump, the high-pressure pump Stop driving and complete dehydration ,
Furthermore, after the moving time of the piston of the high-pressure pump becomes long, it is determined as an abnormal state when the moving time of the piston of the high-pressure pump becomes short. Method. In the operation method of the high pressure pump of the filter press type dehydrator according to claim 1, after converting the moving time of the piston of the high pressure pump into the moving speed of the piston, the moving time of the piston of the high pressure pump becomes long, Instead of determining that the movement time of the piston of the high-pressure pump is shortened as an abnormal state, the movement speed of the piston of the high-pressure pump is increased after the movement speed of the piston of the high-pressure pump is decreased. A method of operating a high-pressure pump of a filter press dehydrator characterized by determining an abnormal state .

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